Description of Minerals. Strictly so called, is completed. But were we to stop here, the utility of the science, if it would be entitled to the name of science, could hardly be considered as very great. We must therefore apply chemistry to discover the ingredients of which minerals are composed, and to detect, if possible, the laws which these ingredients have observed in their combination. Thus we shall really extend our knowledge of inorganic nature, and be enabled to apply that knowledge to the improvement of almost every art and manufacture.

Mineralogy naturally divides itself into three parts. The first treats of the method of describing minerals; the second, of the method of arranging them; and the third exhibits them in a system described and arranged according to the rules laid down in the two first parts. These three parts shall be the subjects of the following chapters; and we shall finish the article with a chapter on the chemical analysis of minerals.

CHAP. I. OF THE DESCRIPTION OF MINERALS.

Nothing, at first sight, appears easier than to describe a mineral, and yet, in reality, it is attended with a great deal of difficulty. The mineralogical descriptions of the ancients are so loose and inaccurate, that many of the minerals to which they allude cannot be ascertained; and consequently their observations, however valuable in themselves, are often, as far as respects us, altogether lost. It is obvious, that to distinguish a mineral from every other, we must either mention some peculiar property, or a collection of properties, which exist together in no other mineral. These properties must be described in terms rigidly accurate, which convey precise ideas of the very properties intended, and of no other properties. The smallest deviation from this would lead to confusion and uncertainty. Now it is impossible to describe minerals in this manner, unless there be a peculiar term for each of their properties; and unless this term be completely understood. Mineralogy therefore must have a language of its own; that is to say, it must have a term to denote every mineralogical property, and each of these terms must be accurately defined. The language of mineralogy was invented by the celebrated Werner of Freyberg, and first made known to the world by the publication of his treatise on the external characters of minerals. Of this language we shall give a view in the following general description of the properties of minerals (A).

The properties of minerals may be divided into two classes:

1. Properties discoverable without destroying the texture of the mineral; 2d, Properties resulting from the action of other bodies on it. The first class has, by Werner and his disciples, been called external properties, and by some French writers physical; the second class has been called chemical.

The external properties may be arranged under the following heads:

I. By figure is meant the shape or form which a mineral is observed to have. The figure of minerals is either regular, particular, or amorphous. 1. Minerals which assume a regular figure are said to be crystallized*. The sides of a crystal are called faces; the sharp line formed by the inclination of two faces is called an edge; and the corner, or angle, formed by the meeting of several edges in one point, is called a solid angle, or simply an angle. Thus a cube has six faces, twelve edges, and eight angles. 2. Some minerals, though not crystallized, affect a particular figure. These particular figures are the following: Globular, like a globe; oval, like an oblong spheroid; ovate, like an egg; cheese-shaped, a very flattened sphere; almond-shaped, like an almond; centricular, like a double convex lens, compressed and gradually thinner towards the edges; coniciform, like a wedge; nodulous, having depressions and protuberances like a potatoe; botryoidal, like grapes closely pressed together; dentiform, longish and tortuous, and thicker at the bottom than the top; wireform, like a wire; capillary, like hair, finer than the preceding; retiform, threads interwoven like a net; dendritic, like a tree, having branches issuing from a common stem; shrubform, branches not arising from a common stem; coralloid, branched like coral; flutatilical, like scales; circinated, like a club, long, and thicker at one end than another; fasciform, long straight cylindrical bodies, united like a bundle of rods; tubular, cylindrical and hollow. 3. When minerals have neither a regular nor particular shape, they are said to be amorphous.

II. By surface is meant the appearance of the external surface of minerals. The surface is either uneven, composed of small unequal elevations and depressions; feathery, having very small sharp and rough elevations, more easily felt than seen; drusy, covered with very minute crystals; rough, composed of very minute blunt elevations, easily distinguishable by the feel; scaly, composed of very minute thin scale-like leaves; smooth, free from all inequality or roughness; specular, having a smooth polished surface like a mirror; or streaked, having elevated, straight, and parallel lines. This last character is confined to the surface of crystals. The streaks are either transverse; longitudinal; alternate, in different directions on different faces; plumose, running from a middle rib; or decussated, crossing each other.

III. By transparency is meant the proportion of transmitted light which minerals are capable of transmitting. They are transparent or pellucid, when objects can be seen distinctly through them; diaphanous, when objects are seen

(a) The fullest account of Werner's external characters which we have seen in the English language, has been given by Dr Townson in his Philosophy of Mineralogy. We have availed ourselves of this book, in order to exhibit some of the latest improvements of Werner and his disciples. The reader may also consult Werner's Treatise, published at Leipzig in 1774; or the French translation published at Dijon in 1790. See also Rosé de Lisle. Des caratères extérieurs des minéraux. And Haüy, Traité d'hist. Nat. II, 56. When opaque minerals become transparent in water, they are called hydrophous. When objects are seen double through a transparent mineral, it is said to refract doubly.

IV. The colours of minerals may be reduced to eight classes.

1. Whites. - Snow white. Pure white. - Reddish white. White with a light tint of red. - Yellowish white. White with a light tint of yellow. - Silver white. Yellowish white with a metallic lustre. - Greyish white. White with a light tint of black. - Greenish white. White with a light tint of green. - Milk white. White with a light tint of blue. - Tin white. Milk white of a metallic lustre.

2. Greys. - Bluish grey. Grey with a little blue. - Lead grey. Bluish grey with a metallic lustre. - Pearl grey. Light grey with a slight mixture of violet blue. - Smoke grey. Dark grey with a little blue and brown. - Greenish grey. Light grey tinged with green. - Yellowish grey. A light grey tinged with yellow. - Steel grey. A dark grey with a light tint of yellow and a metallic lustre. - Black grey. The darkest grey with a tint of yellow.

3. Blacks. - Greyish black. Black with a little white. - Brownish black. Black with a tint of brown. - Black. Pure black. - Iron black. Pure black with a small mixture of white and a metallic lustre. - Bluish black. Black with a tint of blue.

4. Blues. - Indigo blue. A dark bluish blue. - Prussian blue. The purest blue. - Azure blue. A bright blue with scarce a tint of red. - Smalt blue. A light blue. - Violet blue. A mixture of azure blue and carmine. - Lavender blue. Violet blue mixed with grey. - Sky blue. A light blue with a slight tint of green.

5. Greens. - Verdigris green. A bright green of a bluish cast. - Seagreen. A very light green, a mixture of verdigris green and grey. - Beryl green. The preceding, but of a yellowish cast. - Emerald green. Pure green. - Grafs green. Pure green with a tint of yellow. - Apple green. A light green formed of verdigris green and white. - Leek green. A very dark green with a cast of brown. - Blackish green. The darkest green, a mixture of leek green and black.

6. Yellows. - Sulphur yellow. A light greenish yellow. - Brals yellow. The preceding, with a little less green and a metallic lustre. - Lemon yellow. Pure yellow. - Gold yellow. The preceding with a metallic lustre. - Honey yellow. A deep yellow with a little reddish brown. - Wax yellow. The preceding, but deeper. - Pyritaceous. A pale yellow with grey. - Straw yellow. A pale yellow, a mixture of sulphur yellow and reddish grey. - Wine yellow. A pale yellow with a tint of red. - Ochre yellow. Darker than the preceding, a mixture of lemon yellow with a little brown. - Habella yellow. A pale brownish yellow, a mixture of pale orange with reddish brown. - Orange yellow. A bright reddish yellow, formed of lemon yellow and red.

7. Reds. - Aurora red. A bright yellow red, a mixture of scarlet and lemon yellow. - Hyacinth red. A high red like the preceding, but with a shade of brown. - Brick red. Lighter than the preceding; a mixture of aurora red and a little brown. - Scarlet red. A bright and high red with scarce a tint of yellow. - Copper red. A light yellowish red with the metallic lustre. - Blood red. A deep red, a mixture of crimson and scarlet. - Carmine red. Pure red verging towards a cast of blue. - Cochineal red. A deep red; a mixture of carmine with a little blue and a very little grey. - Crimson red. A deep red with a tint of blue. - Flesh red. A very pale red of the crimson kind. - Rose red. A pale red of the cochineal kind. - Peach blossom red. A very pale whitish red of the crimson kind. - Mordoré. A dark dirty crimson red; a mixture of crimson and a little brown. - Brownish red. A mixture of blood red and brown.

8. Browns. - Reddish brown. A deep brown inclining to red. - Clove brown. A deep brown with a tint of carmine. - Yellowish brown. A light brown verging towards ochre yellow. - Umber brown. A light brown, a mixture of yellowish brown and grey. - Hair brown. Intermediate between yellow brown and clove brown with a tint of grey. - Tombac brown. A light yellowish brown, of a metallic lustre, formed of gold yellow and reddish brown.

(n) After Mr Kirwan, we have denoted these three degrees of transparency by the figures 4, 3, 2. When a mineral is subdiaphanous only at the edges, that is denoted by the figure 1. Opacity is sometimes denoted by o. Liver brown. A dark brown; blackish brown with a tint of green.

Blackish brown. The darkest brown.

Colours, in respect of intensity, are either dark, deep, light, or pale. When a colour cannot be referred to any of the preceding, but is a mixture of two, this is expressed by saying, that the prevailing one verges towards the other, if it has only a small tint of it; palles into it, if it has a greater.

V. By the scratch or streak, is meant the mark left when a mineral is scratched by any hard body, as the point of a knife. It is either similar, of the same colour with the mineral; or different, of a different colour.

VI. Lustre, is the gloss or brightness which appears on the external surface of a mineral, or on its internal surface when fresh broken. The first is called external, the second internal lustre. Lustre is either common, that which most minerals possess; silky, like that of silk or mother-of-pearl; waxy, like that of wax; greasy, like that of grease; or metallic, like that of metals.

As to the degree, the greatest is called splendid, the next shining, the third dull; and when only a few scattered particles shine, the lustre is called dull (c).

VII. We have used figures to denote the comparative hardness of bodies; for an explanation of which, we refer to the article Chemistry, Vol. I. p. 224, of this Supplement.

VIII. With respect to ductility and brittleness, minerals are either malleable; flexible, capable of being cut without breaking, but not malleable; flexible, capable of being bent, and when bent retaining their shape; or elastic, capable of being bent, but recovering their former shape. Minerals destitute of these properties are brittle. Brittle minerals, with respect to the ease with which they may be broken, are either very tough, tough, fragile, or very fragile.

IX. By fracture is meant the fresh surface which a mineral displays when broken. It is either flat, without any general elevation or depression; or conchoïdal, having wide extended roundish hollows and gentle ridges. When these are not very evident, the fracture is called flat conchoïdal; when they are small, it is called small conchoïdal; and when of great extent, great conchoïdal.

The fracture may also be even, free from all asperities; uneven, having many small, sharp, abrupt, irregular elevations and inequalities; and from the size of these, this fracture is denominated coarse, small, or fine; splintery, having small, thin, half detached, sharp edged splinters, according to the size of which this fracture is denominated coarse or fine; or rugged, having many very minute sharp hooks, more sensible to the hand than the eye.

X. By texture is meant the internal structure or disposition of the matter of which a mineral is composed, which may be discovered by breaking it. The texture is either compact, without any distinguishable parts, or the appearance of being composed of smaller parts; earthy, composed of very minute almost imperceptible rough parts; granular, composed of small flakelets grains;

(c) These four degrees have been denoted by Kirwan by the figures 1, 3, 5, 7, and no lustre by o. We have imitated him in the present article. present imperfect state of mineralogy, as is more probable, we do not take upon us to determine. But surely the want of success, which has hitherto attended all attempts to combine the two arrangements, ought to suggest the propriety of separating them. By adhering strictly to one language, the trouble of studying two different systems would be entirely prevented. They would throw mutual light upon each other: the artificial system would enable the student to discover the names of minerals; the natural would enable him to arrange them, and to study their properties and uses.

The happy arrangement of Cronstedt, together with the subsequent improvements of Bergman, Werner, Kirwan, Haüy, and other celebrated mineralogists, has brought the natural system of mineralogy to a considerable degree of perfection. But an artificial system is still a desideratum; for excepting Linnæus, whose lucubrations was precluded by the state of the science, no one has hitherto attempted it. Though we are very far from thinking ourselves sufficiently qualified for undertaking such a task, we shall nevertheless venture, in the next chapter, to sketch out the rudiments of an artificial system. The attempt, at least, will be laudable, even though we should fail.

**CHAP. III. Artificial System.**

Minerals may be divided into six classes:

1. Minerals that cannot be fused by the blow-pipe per se. 2. Minerals fusible per se by the blow-pipe. 3. Minerals fusible by the blow-pipe per se when exposed to the blue flame, but not when exposed to the yellow flame. 4. Minerals fusible per se by the blow-pipe; and when in fusion, partly evaporating in a visible smoke. 5. Minerals which totally evaporate before the blow-pipe. 6. Minerals totally soluble in muriatic acid with effervescence, the solution colourless.

Under these heads we shall arrange the subjects of the mineral kingdom.

**Class I. INFUSIBLE.**

**ORDER I. Specific gravity from 16 to 12.**

*Genus I.* Colour whitish iron grey.

Species 1. Native platinum.

**ORDER II. Sp. gr. 8.5844 to 7.006.**

*Genus I.* Attracted by the magnet.

Species 1. Native iron.

*Genus II.* Not attracted by the magnet.

Species 1. Native copper.

Flexible and malleable. Colour usually red.

Species 2. Wolfram.

Brittle. Colour usually brown or black.

**ORDER III. Sp. gr. from 6.4509 to 5.8.**

*Genus I.* Forms a blue glass with microcosmic salt, which becomes colourless in the yellow, but recovers its colour in the blue flame.

Species 1. Tungstal of lime.

*Genus II.* Forms with microcosmic salt a permanently coloured bead.

Species 1. Sulphuret of cobalt.

**ORDER IV. Sp. gr. from 4.8 to 4.5.**

*Genus I.* Tinges borax dark green.

Species 1. Common magnetic iron stone.

*Genus II.* Tinges borax reddish brown.

Species 1. Grey ore of manganese.

**ORDER V. Sp. gr. from 4.4165 to 3.092.** Infusible with fixed alkalies.

*Genus I.* Hardness 20.

Species 1. Diamond.

*Genus II.* Hardness 15 to 17. Causes single refraction.

Species 1. Topaz.

Species 2. Corundum.

**Genus III.** Hardness 13. Single refraction.

Species 1. Ruby.

Crystallizes in octahedrons.

**Genus IV.** Hardness 12. Single refraction.

Species 1. Chrysoberyl.

**Genus V.** Hardness 12. Causes double refraction. Becomes electric when heated.

Species 1. Topaz.

**Genus VI.** Hardness 10 to 16. Double refraction.

Species 1. Zircon.

**Genus VII.** Hardness 6 to 9. Feels greasy.

Species 1. Cyanite.

**Genus VIII.** Hardness 9 to 10. Feel not greasy. Double refraction. Sp. gr. 3.283 to 3.285.

Species 1. Chrysoberyl.

**Genus IX.** Hardness 12. Infusible with borax. Colour of large masses black, of thin pieces deep green.

Species 1. Ceylonite.

*(Phosphat of lime.)*

**ORDER VI. Sp. gr. from 2.9829 to 1.987.** Infusible with fixed alkalies.

*Genus I.* Hardness 12.

Species 1. Emerald.

*Genus II.* Hardness 10.

Species 1. Jade.

**Genus III.** Hardness 6 to 7. Somewhat transparent.

Species 1. Phosphat of lime.

Before the blow-pipe becomes surrounded with a luminous green vapour.

**Genus IV.** Hardness 6. Opaque.

Species 1. Micarelle.

**Genus V.** Stains the fingers. Colour lead grey.

Species 1. Plumbago.

Spanish wax rubbed with plumbago does not become electric; or if it does, the electricity is negative. Streak lead grey, even on earthen ware.

**ORDER VII. Sp. gr. from 4.7385 to 4.569.** Fusible with fixed alkalies.

*Genus I.* Stains the fingers. Colour lead grey.

Species 1. Molybdena.

Spanish wax rubbed with molybdena becomes positively electric. Streak on earthen ware yellowish green.

**ORDER VIII. Sp. gr. from 4.1668 to 2.479.** Fusible with fixed alkalies.

*Hardness from 10 to 12.*

*Genus.* Genus I. Usually white. Crystals dodecahedrons. Double refraction. Fracture imperfectly conchoidal or splintery. Brittle.

Sp. 1. Quartz.

Genus II. Usually dark brown. Fracture perfectly conchoidal. Brittle. Easily breaks into splinters.

Sp. 1. Flint.

Genus III. Not brittle. Fracture even or imperfectly conchoidal.

Sp. 1. Chalcedony.

Sp. 2. Jasper.

Genus IV. Forms with potash a violet glass, with soda or borax a brown glass, with microcosmic salt a honey yellow glass. Colour green. Amorphous.

Sp. 1. Chrysopraesum.

Genus V. Tinges soda red. The colour disappears before the blue flame, and returns before the yellow flame.

Sp. 1. Oxide of manganese and barites.

Sp. 2. Black ore of manganese.

Sp. 3. Carbonate of manganese.

(Brown ore of iron. Red ore of iron.)

** Hardness 9 to 3.

Genus VI. Flexible and elastic in every direction.

Sp. 1. Elastic quartz.

Genus VII. Emits white flakes before the blowpipe.

Sp. 1. Blende.

Genus VIII. Becomes electric when heated.

Sp. 1. Calamine.

Genus IX. Tinges borax green. Blackens before the blowpipe.

Sp. 1. Mountain blue.

Colour blue.

Sp. 2. Green carbonate of copper.

Colour green.

Genus X. Tinges borax green. Becomes attractive by the magnet by the action of the blowpipe.

Sp. 1. Brown iron ore.

Colour brown.

Sp. 2. Red iron ore.

Colour red.

Genus XI. Tinges borax smutty yellow. Becomes brownish black before the blowpipe.

Sp. 1. Carbonate of iron.

Genus XII. Feels greasy.

Sp. 1. Steatites.

(Black ore of manganese. Carbonate of manganese. Mica.)

ORDER IX. Sp. gr. from 2.39 to 1.7.

Genus I. Lustre glaify.

Sp. 1. Opal.

Sp. 2. Hyalite.

Genus II. Lustre greasy.

Sp. 1. Pitchstone.

Genus III. Lustre waxy or pearly.

Sp. 1. Staurolite.

Class II. Fusible.

ORDER I. Sp. gr. from 19 to 10.

Genus I. Colour Yellow.

Sp. 1. Native gold.

Genus II. Colour white.

Sp. 1. Native Silver.

Genus III. Colour yellowish white.

Sp. 1. Alloy of silver and gold.

ORDER II. Sp. gr. from 7.86 to 4.5.

Genus I. Flexible and malleable.

Sp. 1. Sulphuret of silver.

** Brittle.

Genus II. Tinges borax white.

Sp. 1. Tinstone.

Genus III. Tinges borax green.

Sp. 1. Sulphuret of copper.

Colour bluish grey.

Sp. 2. Chromat of lead.

Colour aurora red.

Sp. 3. Purple copper ore.

Colour purple.

Genus IV. Tinges borax faint yellow. Becomes black when exposed to the vapour of sulphuret of ammonia.

Sp. 1. Galena.

Colour bluish grey. Lustre metallic. Fragments cubic.

Sp. 2. Black lead ore.

Colour black. Lustre metallic.

Sp. 3. Lead ochre.

Colour yellow, grey, or red. Lustre o.

Sp. 4. Carbonate of lead.

Colour white. Lustre waxy.

Sp. 5. Phosphat of lead.

Usually green. Lustre waxy. After fusion by the blowpipe crystallizes on cooling.

Sp. 6. Molybdate of lead.

Colour yellow. Streak white. Lustre waxy.

ORDER III. Sp. gr. from 4.35 to 3.

** Hardness 14 to 9.

Genus I. Melts without frothing into a grey enamel.

Sp. 1. Garnet.

Colour red.

Genus II. Melts into a brownish enamel.

Sp. 1. Short.

Colour black. Opaque.

Genus III. Froths and melts into a white enamel.

Sp. 1. Tourmaline.

Becomes electric by heat.

Genus IV. Froths and melts into a greenish-black enamel.

Sp. 1. Basaltine.

Genus V. Froths and melts into a black enamel.

Sp. 1. Thallite.

Colour dark green.

Sp. 2. Thumestone.

Colour clove brown.

** Hardness 5 to 8.

Genus VI. Melts into a transparent glass.

Sp. 1. Flatt of lime.

Powder phosphoresces when thrown on a hot iron.

Genus VII. Melts into a black glass.

Sp. 1. Sp. 1. Hornblende.

Genus VIII. Melts into a black bead with a sulphurous smell, and deposits a blue oxyd on the charcoal.

Sp. 1. Sulphuret of tin.

Genus IX. Melts into a brown glass. Tinges borax violet.

Sp. 1. Asbestos.

Colour green.

Genus X. Melts into a brown (?) glass. When fused with potash, and dissolved in water, the solution becomes of a fine orange yellow.

Sp. 1. Chromat of iron.

Genus XI. Before the blow-pipe yields a bead of copper.

Sp. 1. Red oxyd of copper.

(Sulphuret of copper.)

ORDER IV. Sp. gr. from 2.945 to 2.437.

Genus I. Composed of scales.

Sp. 1. Talk.

Feels greasy. Spanish wax rubbed by it becomes positively electric.

Genus II. Composed of thin plates, easily separable from each other.

Sp. 1. Mica.

Plates flexible and elastic; may be torn but not broken. Spanish wax rubbed by it becomes negatively electric.

Sp. 2. Stilbite.

Plates somewhat flexible. Colour pearl white. Powder renders syrup of violets green. Froths and melts into an opaque white enamel.

Sp. 3. Lepidolite.

Colour violet. Powder white with a tint of red. Froths and melts into a white semitransparent enamel full of bubbles.

Genus III. Texture foliated.

Sp. 1. Felspar.

Fragments rhomboidal. Hardness 9 to 10.

Sp. 2. Leucite.

Always crystallized. White. Powder renders syrup of violets green. Hardness 8 to 10.

Sp. 3. Argentine felspar.

Always crystallized. Two faces dead white, two silvery white.

Sp. 4. Prehnite.

Colour green. Froths and melts into a brown enamel.

Genus IV. Texture fibrous. Fibres easily separated.

Sp. 1. Asbestos.

Feels somewhat greasy.

Genus V. Texture striated.

Sp. 1. Ædelite.

Absorbs water. Froths and melts into a frothy mass.

Genus VI. Texture earthy or compact.

Sp. 1. Lazulite.

Froths and melts into a yellowish black mass. If previously calcined, gelatinizes with acids.

Sp. 2. Borat of lime.

Tinges the flame greenish, froths and melts into a yellowish enamel garnished with small projecting points. If the blast be continued, these dart off in sparks.

ORDER V. Sp. gr. from 2.348 to 0.68.

Genus I. Hardness 10.

Sp. 1. Obsidian.

Colour blackish, in thin pieces green.

Genus II. Hardness 6 to 8.

Sp. 1. Zeolite.

Gelatinizes with acids. Becomes electric by heat.

Genus III. Hardness 3 to 4.

Sp. 1. Amanthus.

Feels greasy. Texture fibrous.

Sp. 2. Mountain cork.

Elastic like cork.

Class III. Fusible by the Blue Flame, Infusible by the Yellow.

Genus I. Sp. gr. from 4.43 to 4.4.

Sp. 1. Sulphate of barites.

Genus II. Sp. gr. from 3.96 to 3.51.

Sp. 1. Sulphate of stromites.

Genus III. Sp. gr. from 2.311 to 2.167.

Sp. 1. Sulphate of lime.

Class IV. Fusible, and partly evaporating.

ORDER I. Sp. gr. from 10 to 5.

Genus I. Colour white or grey. Lustre metallic.

Sp. gr. 9 to 10.

Sp. 1. Native amalgam.

Tinges gold white. Creaks when cut.

Sp. 2. Alloy of silver and antimony.

Powder greyish black.

** Sp. gr. from 6.467 to 5.309.

Sp. 3. Sulphuret of bismuth.

Melts when held to the flame of a candle.

Sp. 4. Dull grey cobalt ore.

Streak bluish grey. Hardness 10.

When struck, emits an arsenical smell. Lustre scarcely metallic.

Genus II. Colour red, at least of the streak.

Sp. 1. Red silver ore.

Burns with a blue flame.

Sp. 2. Hepatic mercurial ore.

Does not flame, but gives out mercury before the blow-pipe.

Genus III. Colour blue.

Sp. 1. Blue lead ore.

Burns with a blue flame and sulphurous smell, and leaves a button of lead.

Genus IV. Colour yellowish green.

Sp. 1. Phosphat and arseniat of lead combined.

When fused by the blow-pipe, crystallizes on cooling.

Genus V. Colour usually that of copper. Sp. gr. ORDER II. Sp. gr. from 4.6 to 3.44.

Genus I. Colour grey. Sp. 1. Grey ore of antimony. Burns with a blue flame, and leaves a white oxide. Sp. 2. Grey copper ore. Crackles before the blow-pipe.

Genus II. Colour yellow. Sp. 1. Pyrites. Burns with a blue flame and sulphurous smell, and leaves a brownish bead. Sp. 2. Yellow copper ore. Melts into a black mass.

CLASS V. EVAPORATING.

ORDER I. Sp. gr. 13.6.

Genus I. Fluid. Sp. 1. Native mercury.

ORDER II. Sp. gr. from 10 to 5.49.

Genus I. Colour red. Sp. 1. Native cinnabar. Genus II. Colour white or grey. Lustre metallic. Sp. 1. Native bismuth. Melts into a white bead, and then evaporates in a yellowish white smoke. Sp. gr. 9 to 9.5. Sp. 2. Native antimony. Melts and evaporates in a grey smoke. Sp. gr. 6.6 to 6.8. Sp. 3. Native arsenic. Evaporates without melting, and gives out a garlic smell.

ORDER III. Sp. gr. from 4.8 to 3.33.

Genus I. Colour red. Sp. 1. Red antimonial ore. Melts with a sulphureous smell. Sp. gr. 4.7. Sp. 2. Realgar. Melts with a garlic smell. Sp. gr. 3.384.

Genus II. Colour yellow. Sp. 1. Orpiment.

CLASS I. EARTHS AND STONES.

We shall divide this class into three orders. The first order shall comprehend all chemical combinations of earths with each other; the second order, chemical combinations of earths with acids; and the third order, mechanical mixtures of earths or stones. All the minerals belonging to the first order, exhibit the same homogeneous appearance to the eye as if they were simple bodies. We shall therefore, for want of a better name, call the first order *simple*; the second order we shall distinguish by the epithet of *fusine*; and the third we shall call

(n) Corpora mineralia in quatuor species dividuntur, silecet in lapides, et in liquefactiva, sulphurea, et fuses. Et horum quaedam sunt rares substantiae et debilis compositionis, et quaedam fortis substantiae, et quaedam ductilibilia, et quaedam non. Avicenna de congelatione et conglutinatione lapidum, Cap. 3. Theatrum Chemicum, t. iv. p. 997. ORDER I. SIMPLE STONES.

Cronstedt divided this order into nine genera, corresponding to nine earths; one of which he thought composed the stones arranged under each genus. The names of his genera were, calcareous, siliceous, granatine, argillaceous, micaeous, fluorite, olivine, zeolitie, magnesia. All his earths were afterwards found to be compounds, except the first, second, fourth, and ninth. Bergman, therefore, in his Scagiographia, first published in 1782, reduced the number of genera to five; which was the number of primitive earths known when he wrote. Since that period three new earths have been discovered. Accordingly, in the latest systems of mineralogy, the genera belonging to this order amount to eight. Each genus is named from an earth; and they are arranged in the newest Wernerian system, which we have seen, as follows:

1. Jargon genus. 2. Siliceous genus. 3. Glucina genus. 4. Argillaceous genus. 5. Magnesian genus. 6. Calcaceous genus. 7. Barytic genus. 8. Strontian genus.

Mr Kirwan, in his very valuable system of mineralogy, has adopted the same genera. Under each genus, those stones are placed, which are composed chiefly of the earth which gives a name to the genus, or which at least are supposed to possess the characters which distinguish that earth.

A little consideration will be sufficient to discover that there is no natural foundation for these genera. Most stones are composed of two, three, or even four ingredients; and, in many cases, the proportion of two or more of these is nearly equal. Now, under what genus forever such minerals are arranged, the earth which gives it a name must form the smallest part of their composition. Accordingly, it has not been so much the chemical composition, as the external character, which has guided the mineralogist in the distribution of his species. The genera cannot be said properly to have any character at all, nor the species to be connected by anything else than an arbitrary title. This defect, which must be apparent in the most valuable systems of mineralogy, seems to have arisen chiefly from an attempt to combine together an artificial and natural system. As we have separated these two from each other, it becomes necessary for us to attend more accurately to the natural distribution of genera than has hitherto been done. We have accordingly ventured to form new genera for this order, and we have formed them according to the following rules.

The only substances which enter into the minerals belonging to this order, in such quantity as to deserve attention, are the following:

- Alumina, - Silica, - Magnesia, - Lime, - Barytes, - Zirconia, - Oxyd of iron, - Oxyd of chromium, - Potas,

All those minerals which are composed of the same ingredients we arrange under the same genus. According to this plan, there must be as many genera as there are varieties of combinations of the above substances existing in nature. The varieties in the proportion of the ingredients constitute species. We have not imposed names upon our genera, but, in imitation of Bergman, have denoted each by a symbol. This symbol is composed of the first letter of every substance which enters in any considerable quantity into the composition of the minerals arranged under the genus denoted by it. Thus, suppose the minerals of a genus to be composed of alumina, silica, and oxyd of iron, we denote the genus by the symbol afs. The letters are arranged according to the proportion of the ingredients; that which enters in the greatest proportion being put first, and the others in their order. Thus the genus afs is composed of a considerable proportion of alumina, of a smaller proportion of silica, and contains least of all of iron. By this contrivance, the symbol of a genus contains, within the compass of a few letters, a pretty accurate description of its nature and character. Where the proportions of the ingredients vary in the same genus so much, that the letters which constitute its symbol change their place, we subdivide the genus into parts; and whenever the minerals belonging to any genus become too numerous, advantage may be taken of these subdivisions, and each of them may be formed into a separate genus. At present this seems unnecessary (x).

The following is a view of the different genera belonging to this order, denoted each by its symbol. Every genus is followed by the species included under it; and the whole are in the order which we mean to follow in describing them:

I. a. - Telestia, - Corundum, - Native alumina.

II. amc. - Ruby.

III. aim. - Ceylanite.

IV. s. - Quartz, - Elastic quartz, - Flint, - Opal, - Pitchstone, - Chrysoptilum.

V. r. as. - Topaz, - Somnite, - Shorlite.

VI. r. asl. - Micarcell, - Short, - Granatite.

VII. sap. - Felspar, - Lepidolite, - Leucite.

VIII. sag. - Emerald.

IX. sab. - Staurolite.

X. r. asl. - Chrysoberyl.

1. sal. - Hyalite, - Edelste.

We need hardly remark, that the last three genera of Werner belong to the second order of the first class of this treatise. Genus I. A.

Species 1. Telefia (r).

Oriental ruby, sapphire, and topaz of mineralogists.—Rubis d'orient of De Lille.

Three stones, distinguished from each other by their colour, have long been held in high estimation on account of their hardness and beauty. These stones were known among lapidaries by the names of ruby, sapphire, and topaz, and the epithet oriental was usually added, to distinguish them from other three, known by the same names and the same colours, but very inferior in hardness and beauty. Mineralogists were accustomed to consider these stones as three distinct species, till Romé de Lille observed that they agreed in the form of their crystals, their hardness, and most of their other properties. These observations were sufficient to constitute them one species; and accordingly they were made one species by Romé de Lille himself, by Kirwan, and several other modern mineralogical writers. But this species was defective of a proper name, till Mr Hauy, whose labours, distinguished equally by their ingenuity and accuracy, have contributed not a little to the progress of mineralogy, denominated it telefia, from the Greek word τελεία, which signifies perfect.

The telefia is found in the East Indies, especially in Pegu and the island of Ceylon; and it is most commonly crystallized. The crystals are of no great size: Their primitive form, according to Mr Hauy, is a regular six-sided prism, divisible in directions parallel both to its bases and its sides; and consequently giving for the form of its primitive nucleus, or of its integrant molecule, an equilateral three sided prism. The most usual variety is a dodecahedron, in which the teletia appears under the form of two very long slender six-sided pyramids, joined base to base. The sides of these pyramids are isosceles triangles, having the angle at their vertex $22^\circ 54'$, and each of those at the base $78^\circ 46'$ (g). The inclination of a side of one pyramid to a contiguous side of the other pyramid is $139^\circ 54'$+. In some specimens the summits of the pyramids are wanting, so that the crystal has the appearance of a six-sided prism, somewhat thicker in the middle than towards the extremities*. The three alternate angles at each extremity of this prism are also sometimes wanting, and a small triangular face instead of them, which renders the bases of the supposed prism nine-sided. The inclination of each of these small triangles to the base is $122^\circ 18'$+. For figures of these crystals we refer the reader to Romé de Lille and Hauy*.

The texture of the telefia is foliated, and the joints are parallel to the base of the prism+. Its lustre varies from 3 to 4 (n). Transparency usually 3 or 4, sometimes only 2. It causes only a single refraction. Specific gravity from 4. to 4.288. Hardness from 15 to 17. It is either colourless, or red, yellow or blue. These colours have induced lapidaries to divide the telefia into the three following varieties.

Variety 1. Red telefia.

Oriental ruby.

Colour carmine red, sometimes verging towards violet. Sometimes various colours appear in the same stone, as red and white, red and blue, orange red. Hardness 17. Sp. gr. 4.288.

Variety 2. Yellow telefia.

Oriental topaz.

Colour golden yellow. Transp. 4. Hardness 15. Sp. gr. 4.0106.

Variety 3. Blue telefia.

Oriental sapphire.

Colour Berlin blue, often to very faint that the stone appears almost colourless. Transp. 3, 4, 2. Hardness 17. Sp. gr. 3.991 to 4.083+. This variety is not Green probably the same with the sapphire of the ancients. Their sapphire was distinguished by gold-coloured spots, none of which are to be seen in the sapphire of the moderns.

A specimen of this last variety, analysed by Mr Klaproth, was found to contain in 100 parts,

- 98.5 alumina, - 1.0 oxyd of iron, - 0.5 lime,

100.0.

The colouring matter of all these varieties is, according to Bergman's experiments, iron, in different states of oxidation. He found that the topaz contained .06, the ruby .13, and the sapphire .02 of that metal+. But when these experiments were made, the analysis of stones was not arrived at a sufficient degree of perfection to ensure accuracy. No conclusion, therefore, can be drawn from these experiments, even though we were certain that they were made upon the real varieties of telefia.

Species Species 2. Corundum (1).

Corundum of Gmelin—Adamantine spar of Klaproth and Kirwan—Corindon of Hauy—Corindum of Woodward.

This stone, though it appears to have been known to Mr. Woodward, may be said to have been first distinguished from other minerals by Dr. Black. In 1768, Mr. Berry, a lapidary in Edinburgh, received a box of it from Dr. Anderson of Madras. Dr. Black ascertained, that these specimens differed from all the stones known to Europeans; and, in consequence of its hardness, it obtained the name of adamantine spar. Notwithstanding this, it could scarcely be said to have been known to European mineralogists till Mr. Greville of London, who has done so much to promote the science of mineralogy, obtained specimens of it, in 1784, from India, and distributed them among the most eminent chemists, in order to be analysed. Mr. Greville also learned, that its Indian name was Corundum. It is found in Indostan, not far from the river Cavery, which is south from Madras, in a rocky matrix, of considerable hardness, partaking of the nature of the stone itself*. It occurs also in China; and a substance, not unlike the matrix of corundum, has been found in Terce, one of the western islands of Scotland†.

The corundum is usually crystallized. Its primitive form, discovered by Mr. Hauy and the Count de Bourbon*, is a rhomboidal parallelopiped, whose sides are equal rhombs, with angles of 86° and 94°, according to Bozon, or whose diagonals are to each other as \( \sqrt{17} \) to \( \sqrt{15} \), according to Hauy; which is very nearly the same thing†. The most common variety, for the primitive form has never yet been found, is the regular six-sided prism, the alternate angles of which are sometimes wanting‡, and the triangular faces, which occupy their place, are inclined to the base at an angle of 122° 34′†. Sometimes the corundum is crystallized in the form of a six-sided pyramid, the apex of which is generally wanting. For a description and figure of these, and all the other varieties of corundum hitherto observed, we refer the reader to the dissertation of the Count de Bourbon on the subject*.

The texture of the corundum is foliated, and the natural joints are parallel to the faces of the primitive rhomboidal parallelopiped. Lustre, when in the direction of the laminae, 3; when broken across, 0. Opaque, except when in very thin pieces. Hardness 15. Sp. gr. from 3.710 to 4.180†. Colour grey, often with various shades of blue and green.

According to the analysis of Klaproth, the corundum of India is composed of:

\[ \begin{align*} & 89.5 \text{ alumina}, \\ & 5.5 \text{ silica}, \\ & 1.25 \text{ oxyd of iron}, \end{align*} \]

\[ 96.25 \text{ ‰}. \]

A specimen from China of

\[ \begin{align*} & 84.0 \text{ alumina}, \\ & 6.5 \text{ silica}, \\ & 7.5 \text{ oxyd of iron}, \end{align*} \]

\[ 98.0 \text{ ‰}. \]

Notwithstanding the quantity of silica and of iron which these analyses exhibit in the corundum, we have been induced to include it in the present genus, on account of the strong resemblance between it and the third variety of telesta. The striking resemblance between the crystals of telesta and corundum will appear evident, even from the superficial description which we have given; and the observations of De Bourbon* render this resemblance still more striking. It is not improbable, therefore, as Mr. Greville and the Count de Bourbon have suggested, that corundum may be only a variety of telesta, and that the seeming difference in their ingredients is owing to the impurity of those specimens of corundum which have hitherto been brought to Europe. Let not the difference which has been found in the primitive form of these stones be considered as an insuperable objection, till the subject has been again examined with this precise object in view; for nothing is easier than to commit an oversight in such difficult examinations.

Species 3. Native alumina (x).

This substance has been found at Halles in Saxony mines, in compact kidney-form masses. Its consistence is earthy. Lustre c. Opaque. Hardness 4. Brittle. Sp. gr. moderate. Feels soft, but meagre. Adheres very slightly to the tongue. Stains very slightly. Colour pure white. Does not readily diffuse itself in water.

It consists of pure alumina, mixed with a small quantity of carbonat of lime, and sometimes of sulphat of lime†.

Genus II. anc.

Species 1. Ruby (r).

Spinel and balas. Ruby of Kirwan—Ruby of Hauy—Rubis spinelle octohedre of De Lisle—Spinellus of Gmelin.

This stone, which comes from the island of Ceylon, is usually crystallized. The primitive form of its crystals is a regular octohedron, composed of two four-sided pyramids applied base to base, each of the sides of which is an equilateral triangle‡ (m). In some cases‡ fig. 5, two opposite sides of the pyramids are broader than the other two; and sometimes the edges of the octohedron are wanting, and narrow faces in their place. For figures and descriptions of these, and other varieties of these crystals, we refer the reader to Romé de Lisle and the Abbé Effner*.

The texture of the ruby is foliated. Its lustre is 3.226. Transp. 3.4. It causes a single refraction. Hardness 13. Sp. gr. 3.770† to 3.625‡. Colour red; if deep, the ruby is usually called balas; if pale rosy, spinelli.

C c 2

---

(1) See Kirwan's Mineralogy, I.—Klaproth in Beob. der Berlin, VIII. 295, and Beiträge, I. 47.—Mr. Greville and the Count de Bourbon in the Philosophical Transactions 1798, p. 403, and in Nicholson's Journal, II. 540, and III. 5.—Mr. Hauy Jour. de Phys. XXX. 193, and Jour. de Min. N° XXVIII. 262.

(2) See Kirwan's Mineralogy, I. 175, and Schreber, 15. Stück, p. 209.

(3) See Kirwan's Min. I. 253.—Romé de Lisle, II. 224.—Klaproth Beob. der Berlin, III. 336, and Beiträge, II. 1.—Vauquelin Ann. de Chim. XXVII. 3. and XXXI. 141.

(4) We shall afterwards distinguish this octohedron either by the epithet regular or aluminaform, because it is the well-known form of crystals of alum. The ruby, according to the analysis of Vauquelin, is composed of:

- 86.00 alumina, - 8.50 magnesia, - 5.25 chromic acid.

99.75

The ancients seem to have clasped this stone among their hyacinths.

GENUS III. AIM.

SPECIES I. Ceylanite.

The mineral denominated ceylanite, from the island of Ceylon, from which it was brought into Europe, had been observed by Romé de Lisle; but was first described by La Metherie in the Journal de Physique for January 1793.

It is most commonly found in rounded masses; but sometimes also crystallized. The primitive form of its crystals is a regular octohedron: it commonly occurs under this form, but more commonly the edges of the octohedron are wanting, and small faces in their place.

The fracture of the ceylanite is conchoïdal*. Its internal lustre is glaify. Nearly opaque, except when in very thin pieces. Hardness 12. Sp. gr. from 3.7647† to 3.793‡. Colour of the mass, black; of very thin pieces, deep green. Powder, greenish grey.

According to the analysis of Defonts the ceylanite is composed of:

- 68 alumina, - 16 oxyd of iron, - 12 magnesia, - 2 silica.

98

GENUS IV. s.

SPECIES I. Quartz.

This stone, which is very common in most mountainous countries, is sometimes crystallized, and sometimes amorphous. The primitive form of its crystals, according to Mr Hauy, is a rhomboïdal parallelopiped; the angles of whose thombs are 93° 22', and 86° 38'; so that it does not differ much from a cube*. The most common variety is a dodecahedron†, composed of two fix-sided pyramids, applied base to base, whose sides are isosceles triangles, having the angle at the vertex 40°, and each of the angles at the base 70°; the inclination of a side of one pyramid to the contiguous side of the other pyramid is 104°. There is often a fixed prism interposed between the two pyramids, the sides of which always correspond with those of the pyramids†. For a description and figure of the other varieties of quartz crystals, and for a demonstration of the law which they have followed in crystallizing, we refer the reader to Romé de Lisle† and Mr Hauy†.

The texture of quartz is more or less foliated. Fracture, conchoïdal or splintery. Its lustre varies from 3 to 1, and its transparency from 4 to 1; and in some cases it is opaque. It causes a double refraction. Hardness, from 10 to 11. Sp. gr. from 2.64 to 2.67, and in one variety 2.691. Its colour is exceedingly various; a circumstance which has induced mineralogists to divide it into numerous varieties. Of these the following are the chief:

1. Pure colourless, perfectly transparent crystallized quartz, having much the appearance of artificial crystal; known by the name of rock crystal.

2. Quartz less transparent, and with a splintery fracture, has usually been distinguished by the name of quartz, and separated from rock crystal. As there is no occasion for this separation, we have, in imitation of Mr Hauy, chosen the word quartz for the specific name, comprehending under it all the varieties.

3. Blood red quartz; formerly called compoïsta hyacinth, and by Hauy quartz hematoïde. It owes its colour to oxyd of iron. The mineral known to mineralogists by the name of smogle, and considered by them as a variety of jasper, has been discovered by Dolomieu to be merely this variety of quartz in an amorphous state*.

4. Yellow quartz; called faïse topaz.

5. Ruby red quartz; called Bohemian ruby.

For a fuller enumeration of these varieties, we refer the reader to Smeller's Mineralogy†, Kirwan's Mineralogy‡, and Gmelin's edition of the Systema Naturae of Linnæus§. This last writer, however, has arranged several minerals under quartz which do not belong to it.

Pure quartz is composed entirely of silica; but some of the varieties of this species are contaminated with metallic oxyds, and with a small quantity of other earths.

SPECIES 2. Elastic Quartz (n).

This singular stone is moderately elastic, and flexible quartz, in every direction. Texture, earthy. Lustre, o or i. Hardness, 9. Brittle. Sp. gr. 2.624. Colour, greyish white. Phosphoresces when scraped with a knife in the dark. The specimen analyzed by Mr Klaproth contained:

- 96.5 silica, - 2.5 alumina, - 5 oxyd of iron,

99.5†

SPECIES 3. Flint (o).

Pyromachus—Pierre a fusil—Silix of Hauy.

This stone, which has become so necessary in modern war, is found in pieces of different sizes, and usually of a figure more or less globular, commonly among chalk, and often arranged in some kind of order. In Saxony it is said to have been found crystallized in hexahedrons, composed of two low three-sided pyramids applied base to base*.

Its texture is compact. Its fracture, smooth conchoïdal. Lustre, external o, the stones being always covered by a white crust; internal i, inclining to greasy. Transp. 2; when very thin, 3. Hardness, 10 or 11. Sp. gr. from 2.58 to 2.63. Colour varies from honey yellow to brownish black. Very brittle, and splits into splinters in every direction. Two pieces of flint rubbed smartly together phosphoresce, and emit a peculiar odour. When heated it decrepitates, and becomes white and opaque. When exposed long to the air

Kirwan's Min. I. 316.—Gerhard Mem. Berlin, 1783, 107.—Klaproth's Beiträge 2 Band. 113. See also Jour. de Phys. XLI. 91.

Kirwan's Min. I. 301.—Dolomieu Jour de Min. No XXXIII. 693. and Salivet, ibid. 713. These last gentlemen give the only accurate account of the method of making gun flints. A specimen of flint analysed by Klaproth contained:

- 98.00 silica, - .50 lime, - .25 alumina, - 0.25 oxyd of iron, - 1.00 water.

100.00

Another specimen analysed by Dolomieu was composed of:

- 97 silica, - 1 alumina and oxyd of iron, - 2 water.

100

The white crust with which flint is enveloped, consists of the same ingredients, and also a little carbonat of lime. Dolomieu discovered that water is essential to flint; for when it is separated by heat the stone loses its properties.

The manufacture of gun flints is chiefly confined to two or three departments in France. The operation is exceedingly simple: a good workman will make 1000 flints in a day. The whole art consists in striking the stone repeatedly with a kind of mallet, and bringing off at each stroke a splinter, sharp at one end and thicker at the other. These splinters are afterward shaped at pleasure, by laying the line at which it is wished they should break, upon a sharp iron instrument, and then giving it repeatedly small blows with a mallet. During the whole operation the workman holds the stone in his hand, or merely supports it on his knee.

**SPECIES 4. Opal (p).**

This stone is found in many parts of Europe. It is usually amorphous. Its fracture is conchoidal, commonly somewhat transparent. Hardness from 6 to 10. Sp. gr. from 1.7 to 2.66. The lowest of its specific gravity, in some cases, is to be ascribed to accidental cavities which the stone contains. These are sometimes filled with drops of water. Some specimens of opal have the property of emitting various coloured rays, with a particular effulgency, when placed between the eye and the light. The opals which possess this property, are distinguished by lapidaries by the epithet oriental; and often by mineralogists by the epithet nobilis. This property rendered the stone much esteemed by the ancients.

**Variety 1. Opal edler—Opalus nobilis.**

Lustre glassy, 3. Transp. 3 to 2. Hardness, 6 to 8. Colour, usually light bluish white, sometimes yellow or green. When heated it becomes opaque, and sometimes is decomposed by the action of the atmosphere. Hence it seems to follow, that water enters essentially into its composition. A specimen of this variety, analysed by Klaproth, contained:

- 90 silica, - 10 water.

100

**Variety 2. Semi-opal.**

Fracture, imperfectly conchoidal. Lustre, glassy 2. Transp. 2 to 3. Hardness, 7 to 9. Its colours are very various, greys, yellows, reds, browns, greens of different kinds.

Specimens of this variety sometimes occur with rifts; these readily imbibe water, and therefore adhere to the tongue. These specimens sometimes become transparent when soaked in water, by imbibing that fluid. They are then called hydrophanes.

**Variety 3. Cat's eye.**

This variety comes from Ceylon, and is seldom seen by European mineralogists till it has been polished by the lapidary. Mr. Klaproth has described a specimen which he received in its natural state from Mr. Greville of London. Its figure was nearly square, with sharp edges, a rough surface, and a good deal of brilliancy.

Its texture is imperfectly foliated. Lustre greasy, 2. Transp. 3 to 2. Hardness 10. Sp. gr. 2.56 to 2.66. Colour, grey; with a tinge of green, yellow or white; or brown, with a tinge of yellow or red. In certain positions it reflects a splendid white, as does the eye of a cat; hence the name of this stone.

Two specimens, analysed by Klaproth, the first from Ceylon, the other from Mslabar, were composed of:

- 95.00 silica, - 1.75 alumina, - 1.50 lime, - 0.25 oxyd of iron.

98.5

**SPECIES 5. Pitchstone §.**

**Menelites.**

This stone, which occurs in different parts of Germany, France, and other countries, has obtained its name from some resemblance which it has been supposed to have to pitch. It is most usually in amorphous pieces of different sizes; and it has been found also crystallized in six-sided prisms, terminated by three-sided pyramids.

Its texture is conchoidal and uneven, and sometimes approaches the splintery. Lustre greasy, from 3 to 1. Transp. 2 to 1, sometimes 0. Hardness 8 to 10. Exceedingly brittle; it yields even to the nail of the finger. Sp. gr. 2.049 to 2.39. Its colours are numerous, greyish black, bluish grey, green, red, yellow of different shades. Sometimes several of these colours appear together in the same stone. A specimen of pitchstone from Mefnil-montant near Paris*, analysed by Mr. Klaproth, contained:

- 85.5 silica, - 11.0 air and water, - 1.0 alumina, - .5 iron, - .5 lime and magnesia.

98.5

**SPECIES 6. Chrysoprasium (q).**

This mineral, which is found in different parts of Chrysoprasium Germany, particularly near Kofemütz in Silecia, is always amorphous. Its fracture is either even or inclining to the splintery. Scarcely any lustre. Transp. 2 to 3. Hardness 10 to 12. Sp. gr. 2.479. Colour, green. In a heat of 130° Wedgwood it whitens and becomes opaque.

---

(* Kirwan's Min. I. 289.—Hauy, Jour. d'Histoire Nat. II. 9. Delius, Nouv. Jour. de Phys. I. 45.) (§ Kirwan's Min. I.—Lehmann, Mem. Berlin, 1755, p. 202.—Klaproth Beiträge, II. 127.) A specimen of this stone, analysed by Mr Klaproth, contained:

- 96.16 silica, - 1.00 oxyd of nickel, - 0.83 lime, - 0.68 alumina, - 0.68 oxyd of iron.

98.15

**Genus V. I. As.**

**Species 1. Topaz (r).**

Occidental ruby, topaz, and sapphire.

The name topaz has been restricted by Mr Hauy to the stones called by mineralogists occidental ruby, topaz, and sapphire; which, agreeing in their crystallization and most of their properties, were arranged under one species by Mr Romé de Lisle. The word topaz, derived from an island in the Red Sea (s), where the ancients used to find topazes, was applied by them to a mineral very different from ours. One variety of our topaz they denominated chrysolite.

The topaz is found in Saxony, Bohemia, Siberia, and Brazil, mixed with other minerals in granite rocks.

It is commonly crystallized. The primitive form of its crystals is a prism whose sides are rectangles, and bases rhombs, having their greatest angles $124^\circ 22'$, and the integral molecule has the same form*; and the height of the prism is to a side of the rhomboidal bases as 3 to 2‡. The different varieties of topaz crystals hitherto observed, amount to 6. Five of these are eight-sided prisms, terminated by four-sided pyramids, or wedge-shaped summits, or by irregular figures of 7, 13, or 15 sides‖; the last variety is a twelve-sided prism, terminated by six-sided pyramids wanting the apex. For an accurate description and figure of these varieties we refer the reader to Mr Hauy †.

The texture of the topaz is foliated. Its lustre is from 2 to 4. Transp. from 2 to 4. It causes a double refraction. Hardness 12 to 14. Sp. gr. from 3.53 to 3.56. The Siberian and Brazil topazes, when heated, become positively electrified on one side, and negatively on the other §. It is infusible by the blowpipe. The yellow topaz of Brazil becomes red when exposed to a strong heat in a crucible; that of Saxony becomes white by the same process. This shews us, that the colouring matter of these two stones is different.

The colour of the topaz is various, which has induced mineralogists to divide it into the following varieties:

1. Red topaz, of a red colour inclining to yellow; called Brazilian or occidental ruby. 2. Yellow topaz, of a golden yellow colour, and sometimes also nearly white; called occidental or Brazil topaz. The powder of this and the following variety causes syrup of violets to assume a green colour‖. 3. Saxon topaz. It is of a pale wine yellow colour, and sometimes greyish white.

---

(a) Kirwan's Min. I. 254.—Pott. Mem. Berlin, 1747, p. 46.—Margraf, ibid. 1776, p. 73. and 160.—Henkel. Ad. Acad. Nat. Cur. IV. 316.

(s) It got its name from *saxum* to fish; because the island was often surrounded with fog, and therefore difficult to find. See Plinius lib. 37, c. 8.

(r) Kirwan's Min. I. 288. Bludheim. Crelle's Annalen, 1792, p. 320.

(u) Kirwan's Min. I. 307.—Wiegleb. Crelle's Annalen, 1787, Band 302.—See also Reuft. Samml. Natur. Hist. Aufsätze, p. 107.

---

4. Aligue marine. It is of a bluish or pale green colour.

5. Occidental sapphire. It is of a blue colour; and sometimes white.

A specimen of white Saxon topaz, analysed by Vaquelin, contained:

- 6% alumina, - 31 silica.

99

**Species 2. Somnite.**

This stone was called somnite by La Metherie, from the mountain Somme, where it was first found. It is somnite, usually mixed with volcanic productions. It crystallizes in six-sided prisms, sometimes terminated by pyramids. Colour white. Somewhat transparent. Sp. gr. 3.74†. Infusible by the blow-pipe. According to the analysis of Vaquelin, it is composed of:

- 49 alumina, - 46 silica, - 2 lime, - 1 oxyd of iron.

98

**Species 3. Shorlite †.**

This stone, which received its name from Mr Klapproth, is generally found, in irregular oblong masses or columns, inserted in granite. Its texture is foliated. Fracture uneven. Lustre 2. Transparency 2 to 1. Hardness 9 to 10. Sp. gr. 3.53. Colour greenish white, or sulphur yellow. Not altered by heat. According to the analysis of Klapproth, it is composed of:

- 50 alumina, - 50 silica.

100

**Genus V. 2 sa.**

**Species 4. Rubellite (r).**

Red flour of Siberia.

This stone is found in Siberia mixed with white quartz. It is crystallized in small needles, which are grouped together and traverse the quartz in various directions. Texture fibrous. Fracture even, inclining to the conchoidal. Transparency 1; at the edges 3. Hardness 10. Brittle. Sp. gr. 3.1. Colour crimson, blood or peach red. By exposure to a red heat it becomes snow white; but loses none of its weight. It tinges soda blue, but does not melt with it.

According to the analysis of Mr Bindheim, it is composed of:

- 57 silica, - 35 alumina, - 5 oxyds of iron and manganese.

97

**Species 5. Hornblate (u).**

Silexite porphyry.

This stone, which occurs in mountains, is generally amorphous; but sometimes also in columns. Structure Species 6. Hornstone (x).

Petroglyph—Chert.

This stone, which makes a part of many mountains, is usually amorphous; but, as Mr Kirwan informs us, it has been found crystallized by Mr Beyer on Schneeberg. Its crystals are six-sided prisms, sometimes terminated by pyramids; hexahedrons, consisting of two three-sided pyramids applied base to base; and cubes, or six-sided plates*. Its texture is foliated. Fracture splintery, and sometimes conchooidal. Lustre o. Transparency 1 to 2. The crystals are sometimes opaque. Hardness 7 to 9. Sp. gr. 2.532 to 2.653. Colour usually dark blue; but hornstone occurs also of the following colours; grey, red, blue, green, and brown of different shades†.

According to Kirwan, it is composed of

- 72 silica, - 22 alumina, - 6 carbonat of lime.

Species 7. Chalcedony.

This stone is found abundantly in many countries, particularly in Iceland and the Faro islands. It is most commonly amorphous, flabelliform, or in rounded masses; but it occurs also crystallized in six-sided prisms, terminated by pyramids, or more commonly in four or six sided pyramids, whose sides are convex. Surface rough. Fracture more or less conchooidal. Lustre t. Somewhat transparent. Hardness 10 to 11. Sp. gr. 2.50 to 2.665. Not brittle.

According to Bergman, the chalcedony of Faroe is composed of

- 84 silica, - 16 alumina, mixed with iron.

Variety 1. Common chalcedony.

Fracture even, inclining to conchoidal. Transparency 2 to 3; sometimes 1. Its colours are various; it is most commonly greyish, with a tint of yellow, green, blue, or pearl; often also white, green, red, yellow, brown, black, or dotted with red. When striped white and black, or brown, alternately, it is called onyx; when striped white and grey, it is called chalcedony. Black or brown chalcedony, when held between the eye and a strong light, appears dark red.

Variety 2. Cornelian.

Fracture conchoidal. Transparency 3 to 1; often cloudy. Its colours are various shades of red, brown, and yellow. Several colours often appear in the same mass. To this variety belong many of the stones known by the name of Scotch pebbles.

Species 8. Jasper (v).

This stone is an ingredient in the composition of jasper, many mountains. It occurs usually in large amorphous masses, and sometimes also crystallized in six-sided irregular prisms. Its fracture is conchooidal. Lustre from 2 to 6. Either opaque, or its transparency is 1. Hardness 9 to 10. Sp. gr. from 2.5 to 2.82. Its colours are various. When heated, it does not decrepitate. It seems to be composed of silica and alumina, and often also contains iron.

Variety 1. Common jasper.

Sp. gr. from 2.58 to 2.7. Its colours are, different shades of white, yellow, red, brown, and green; often variegated, spotted, or veined, with several colours.

Variety 2. Egyptian pebble.

This variety is found chiefly in Egypt. It usually has a spheroidal or flat rounded figure, and is enveloped in a coarse rough crust. It is opaque. Hardness 10. Sp. gr. 2.564. It is chiefly distinguished by the variety of colours, which always exist in the same specimen, either in concentric stripes or layers, or in dots or dendritical figures. These colours are, different browns and yellows, milk white, and isabella green; black also has been observed in dots.

Variety 3. Striped jasper.

This variety is also distinguished by concentric stripes or layers of different colours; these colours are, yellow, brownish red, and green. It is distinguished from the last variety by its occurring in large amorphous masses, and by its fracture, which is nearly even.

Species 9. Tripoli.

This mineral is found sometimes in an earthy form, but more generally indurated. Its texture is earthy. Its fracture often somewhat conchoidal. Lustre o. Generally opaque. Hardness 4 to 7. Sp. gr. 2.680 to 2.529. Absorbs water. Feel, harsh dry. Hardly adheres to the tongue. Takes no polish from the nail. Does not stain the fingers. Colour generally pale yellowish grey, also different kinds of yellow, brown, and white.

It contains, according to Hauffe, 90 parts of silica, 7 alumina, and 3 of iron. A mineral belonging to this species was analyzed by Klapproth, and found to contain

- 66.5 silica, - 7.0 alumina, - 2.5 oxyd of iron, - 1.5 magnesia, - 1.25 lime, - 19. air and water.

97.75

Genus VI. i. ast.

Species 1. Micarell.

This name has been given by Mr Kirwan to a stone Micarell, which former mineralogists considered as a variety of Kirwan's mica. It is found in granite. Its texture is foliated, Mix i. and ii.

(x) Kirwan's Min. I. 303.—Baumer Jour. de Phys. II. 154. and Monnet, ibid. 331.—Wiggles. Crell's Anmals, 1788, p. 45 and 135.

(v) Kirw. Min. I. 309.—Borral Hist. Natur. de Corse.—Henkel Ab. Acad. Nat. Curios. V. 339. Earth and it may be split into thin plates. Lustre metallic. 3.

Species: Opaque. Hardness 6. Sp. gr. 2.080. Colour brownish black. At 153° Wedgwood, it melts into a black compact glass, the surface of which is reddish.

A specimen analysed by Klaproth contained:

- 63.00 alumina, - 29.50 silica, - 6.75 iron.

99.25

Species 2: Short.

No word has been used by mineralogists with less limitation than short. It was first introduced into mineralogy by Cronstedt, to denote any stone of a columnar form, considerable hardness, and a specific gravity from 3 to 3.4. This description applied to a very great number of stones. And succeeding mineralogists, though they made the word more definite in its signification, left it still so general, that under the designation of short almost 20 distinct species of minerals were included.

Mr Werner first defined the word short precisely, and restricted it to one species of stones. We use the word in the sense assigned by him.

Short is found abundantly in mountains, either massive or crystallized, in three or nine sided prisms, often terminated by three sided summits. The sides of the crystals are longitudinally streaked. Its texture is foliated. Its fracture conchoidal. Lustre 1. Opaque. Hardness 10. Sp. gr. 2.92 to 3.212. Colour: black. Streak grey. It does not become electric by heat. When heated to redness, its colour becomes brownish red; and at 127° Wedgwood, it is converted into a brownish compact enamel*. According to Wiegbe, it is composed of:

- 41.25 alumina, - 34.16 silica, - 20.00 iron, - 5.41 manganese.

100.82†

Species 3: Granatite.

Staurolite of Haüy—Pierre de Croix of De Lille—Staurolithe of Lametheric.

We have adopted from Mr Vauquelin the term granatite to denote this stone, because all the other names are ambiguous, having been applied to another mineral possessed of very different properties.

Granatite is found in Galicia in Spain, and Brittany in France. It is always crystallized in a very peculiar form; two six-sided prisms intersect each other, either at right angles or obliquely†. Hence the name crostoflone, by which it was known in France and Spain*. Mr Haüy has proved, in a very ingenious manner, that the primitive form of the granatite is a rectangular prism, whose bases are rhombs, with angles of 129° and 50°; and that the height of the prism is to the greater diagonal of a rhomb as 1 to 6; and that its integrant molecules are triangular prisms, similar to what would be obtained by cutting the primitive crystal in two, by a plane passing vertically through the shorter diagonal of the rhombohedral base. From this structure he has demonstrated the law of the formation of the cruciform varieties*. The colour of granatite is greyish or reddish brown.

According to the analysis of Vauquelin, it is composed of:

- 47.06 alumina, - 30.59 silica, - 15.30 oxyd of iron, - 3.00 lime.

95.95†

Genus VI. 2. SAI.

Species 4: Tourmaline (z).

This stone was first made known in Europe by specimens brought from Ceylon; but it is now found frequently forming a part of the composition of mountains. It is either in amorphous pieces, or crystallized in three or nine sided prisms, with four-sided summits.

Its texture is foliated. Its fracture conchoidal. Internal lustre 2 to 3. Transparency 3 to 4; sometimes only 2 (a). Caules only single refraction*. Hardness 9 to 11. Sp. gr. 3.05 to 3.155. Colour brown, often so dark that the stone appears black; the brown has also sometimes a tint of green, blue, red, or yellow.

When heated to 2000° Fahrenheit, it becomes electric; one of the summits of the crystal negatively, the other positively†. It reddens when heated; and is fusible per se with intumescence into a white or grey enamel.

A specimen of the tourmaline of Ceylon, analysed by Vauquelin, was composed of:

- 40 silica, - 39 alumina, - 12 oxyd of iron, - 4 lime, - 2.5 oxyd of manganese.

97.5†

Species 5: Argentine selspar.

This stone was discovered by Mr Dodun in the black mountains of Languedoc. It is either amorphous, or Argentocrystallized in rhombohedral tables, or six or eight sided felloprisms. Its texture is foliated. Fragments rectangular. Lamina inflexible. Internal lustre 4. Transparency 2. Colour white; two opposite faces of the crystals are silver white, two others dead white. Hardness of the filvery lamina 6, of the rest 9. Brittle. Sp. gr. 2.5. When the flame of the blow-pipe is directed against the edges of the crystal (fluck upon glass), it easily melts into a clear compact glass; but when the flame is directed against the faces, they preserve their lustre, and the edges alone slowly melt.

According to the analysis of Dodun, it is composed of:

- 46 silica, - 36 alumina, - 16 oxyd of iron,

98

When this stone is exposed to the atmosphere, it is apt... This stone forms an essential part of many mountains, and has been long known under the names of glacies marie and Mucovoy glass. It consists of a great number of thin laminae adhering to each other, sometimes of a very large size. Specimens have been found in Siberia nearly 2 yards square (a).

It is sometimes crystallized; its primitive form is a rectangular prism, whose bases are rhombic, with angles of 120° and 60°. Its integrant molecule has the same form. Sometimes it occurs in rectangular prisms, whose bases also are rectangles, and sometimes also in short six-sided prisms; but it is much more frequently seen in plates or scales of no determinate figure or size.

Its texture is foliated. Its fragments flat. The lamellae flexible, and somewhat elastic. Lustre metallic, from 3 to 4. Transparency of the laminae 3 or 4, sometimes only 2 (c). Hardness 6. Very tough. Often absorbs water. Sp. gr. from 2.65 to 2.93. Feels smooth, but not greasy. Powder feels greasy. Colour, when purest, silver white or grey; but it occurs also yellow, greenish, reddish, brown, and black. Mica is fusible by the blow-pipe into a white, grey, green, or black enamel; and this last is attracted by the magnet (n). Spanish wax rubbed by it becomes negatively electric.

A specimen of mica, analysed by Vauquelin, contained:

- 50.00 silica, - 35.00 alumina, - 7.00 oxyd of iron, - 1.35 magnesia, - 1.33 lime, - 94.68.

Mica has long been employed as a substitute for glass. A great quantity of it is said to be used in the Russian marine for panes to the cabin windows of ships; it is preferred, because it is not so liable as glass to be broken by the agitation of the ship.

**Species 7. Talc.**

This stone has a very strong resemblance to mica, and was long considered as a mere variety of that mineral. It occurs sometimes in small loose scales, and sometimes in an indurated form; but it has not hitherto been found crystallized.

Its texture is foliated. The lamellae are flexible, but not elastic. Its lustre is from 2 to 4. Transparency from 2 to 4. Hardness 4 to 6. Sp. gr. when indurated, from 2.7 to 2.8. Feels greasy. Colour most commonly whitish or greenish. Spanish wax rubbed with it becomes positively electric (g).

**Variety 1. Scaly talc.**

*Talcite* of Kirwan.

This variety occurs under the form of small scales, *Suppl. Vol. II. Part I.*

---

(a) Hist. General de Voyageur, T. XVIII. 272, quoted by Haury *Jour. de Min. No XXVIII. 299.*

(b) Black mica is often nearly opaque.

(c) Haury, *ibid.* p. 295. Bergman, however, found pure mica infusible per se; and this has been the case with all the specimens of Mucovoy glass which we have tried.

(e) We suspect, that under this name Mr Haury comprehends *fibrolite* also. Earth and Stones.

Species 10. Resplendent Hornblende.

There are two minerals which Werner considers as varieties of hornblende, and Mr Kirwan as constituting a distinct species. These, till future analyses decide the point, we shall place here under the name of resplendent hornblende, the name given them by Mr Kirwan; and we shall describe them separately.

Variety 1. Labradorite hornblende.

Texture, curved foliated. Lustre, in some positions, o; in others metallic, and from 3 to 4. Opaque. Hardness 8 to 9. Sp. gr. from 3.25 to 3.434. Colour, in most positions, greyish black; in others, it reflects a strong iron grey, sometimes mixed with copper red.

Variety 2. Shiller spar.

Texture foliated. Lustre metallic, 4. Transparency, in thin pieces, 1. Hardness 8 to 9. Sp. gr. 2.882. Colour green, often with a shade of yellow; also golden yellow. In some positions it reflects white, grey, or yellow. At 14° Wedgwood, hardened into a porcelain mass. A specimen, analyzed by Gmelin, was composed of:

- 43.7 silica, - 17.9 alumina, - 23.7 iron, - 11.2 magnesia.

It has been found in the Hartz, stuck in a serpentine rock.

Species 11. Obsidian.

Iceland agate.

This stone is found either in detached masses, or forming a part of the rocks which compose many mountains. It is usually invested with a grey or opaque crust. Its fracture is conchoidal. Its internal lustre 3. Transparency 1. Hardness 10. Sp. gr. 2.348. Colour black or greyish black; when in very thin pieces, green. It melts into an opaque grey mass. According to Bergman, it is composed of:

- 69 silica, - 22 alumina, - 9 iron.

Species 12. Petrified.

Cubic feldspar.

This stone is found in the mass of mountains. It is amorphous. Texture foliated. Fracture splintery. Fragments cubic, or inclining to that form; their faces unpolished. Lustre 2. Transparency partly 2, partly 1. Hardness 9. Sp. gr. 3.081. Colour reddish brown. Does not melt at 160° Wedgwood.

Species 13. Feldspar.

Compact feldspar.

This stone also forms a part of many mountains, and is amorphous. Texture somewhat foliated. Fracture uneven, approaching to the splintery. Lustre 1. Transparency scarce 1. Hardness 9. Colour azure blue, and sometimes brown and green. Streak white. Before the blowpipe, whitens and becomes risty; but is infusible per se.

Genus VII. ssp.

Species 1. Feldspar.

This stone forms the principal part of many of the highest mountains. It is commonly crystallized. Its primitive form, according to De Lille, is a rectangular prism, whose bases are rhombs, with angles of 62° and 118°. Sometimes the edges of the prism are wanting, and faces in their place; and sometimes this is the case also with the acute angles of the rhomb. For a description and figure of these, and other varieties, we refer the reader to Romé de Lisle*, Mr Haug†, and Mr Credill Pini‡.

Its texture is foliated. Its cross fracture uneven. Fragments rhomboidal, and commonly smooth and polished on four sides. Lustre of the polished faces often 3. Transparency from 3 to 1. Hardness 9 to 10. Sp. gr. from 2.437 to 2.7. Gives a peculiar odour when rubbed. It is made electric with great difficulty by friction. Fusible per se into a more or less transparent glass. When crystallized, it decrepitates before the blow pipe.

Variety 1. Pure Feldspar.

Moon stone—Adularia.

This is the purest feldspar hitherto found. It occurs in Ceylon and Switzerland; and was first mentioned by Mr Sage. Lustre nearly 3. Transparency 2 to 3. Hardness 10. Sp. gr. 2.559. Colour white; sometimes with a shade of yellow, green, or red. Its surface is sometimes iridescent.

Variety 2. Common Feldspar.

Lustre of the cross fracture o; of the fracture, in the direction of the laminae, from 2 to 1. Transparency 2 to 1. Colour most commonly flesh red; but often bluish grey, yellowish white, milk white, brownish yellow; and sometimes blue, olive green, and even black.

Variety 3. Labradorite feldspar.

This variety was discovered on the coast of Labrador by Mr Wolfe; and since that time it has been found in Europe. Lustre 2 to 3. Transparency from 1 to 3. Sp. gr. from 2.67 to 2.692. Colour grey. In certain positions, spots of it reflect a blue, purple, red, or green colour.

Variety 4. Continuous feldspar.

This variety most probably belongs to a different species; but as it has not hitherto been analysed, we did not think ourselves at liberty to alter its place.

It is found in large masses. Texture earthy. Fracture uneven, sometimes splintery. Lustre o. Transparency 1. Hardness 10. Sp. gr. 2.609. Colour reddish grey, reddish yellow, flesh red.

A specimen of green feldspar from Siberia, analysed by Vanquelin, contained:

- 62.83 silica, - 17.02 alumina, - 16.00 potash, - 3.00 lime, - 1.00 oxyd of iron.

Species 106. This stone appears to have been first observed by the Abbé Poda, and to have been first described by De Born. Hitherto it has only been found in Moravia in Germany, and Sweden in Sweden. There it is mixed with granite in large amorphous masses. It is composed of thin plates, easily separated, and not unlike those of mica. Lustre, pearly. Transparency between 1 and 2. Hardness 4 to 5. Not easily pulverized. Sp. gr. from 2.816 to 2.8549. Colour of the mass, violet blue; of the thin plates, silvery white. Powder white, with a tint of red. Before the blowpipe, it froths, and melts easily into a white semitransparent enamel, full of bubbles. Dissolves in borax with effervescence, and communicates no colour to it. Effervesces slightly with soda, and melts into a mass spotted with red. With microcosmic salt, it gives a pearl coloured globule.

This stone was first called lilalite from its colour, that of the lily. Klaproth, who discovered its component parts, gave it the name of lepidolite.

It is composed of:

- 53 silica, - 20 alumina, - 18 potash, - 5 fluid of lime, - 3 oxyd of manganese, - 1 oxyd of iron.

---

**Species 3. Leucite**

Vesuvian of Kirwan—White garnet of Vesuvius.

This stone is usually found in volcanic productions, and is very abundant in the neighbourhood of Vesuvius. It is always crystallized. The primitive form of its crystals is either a cube or a rhombohedral dodecahedron, and its integrant molecules are tetrahedrons; but the varieties hitherto observed are all polyhedrons: The most common has a fisheroidal figure, and is bounded by 24 equal and similar trapezoids; sometimes the faces are 12, 18, 36, 54, and triangular, pentagonal, &c. For a description and figure of several of these, we refer the reader to Mr Haüy. The crystals vary from the size of a pin head to that of an inch.

The texture of the leucite is foliated. Its fracture somewhat conchoideal. Lustre 3; when in a state of decomposition 0. Transparency 3 to 2; when decomposing 0. Hardness 2 to 3; when decomposing 5 to 6. Sp. gr. 2.4648. Colour white, or greyish white (ii). Its powder causes syrup of violets to assume a green colour.

It is composed, as Klaproth has shown, of:

- 54 silica, - 23 alumina, - 22 potash.

---

It was by analysing this stone that Klaproth discovered the presence of potash in the mineral kingdom; which is not the least important of the numerous discoveries of that accurate and illustrious chemist.

Leucite is found sometimes in rocks which have never been exposed to volcanic fire; and Mr Dolomieu has rendered it probable, from the substances in which it is found, that the leucite of volcanoes has not been formed by volcanic fire, but that it existed previously in the rocks upon which the volcanoes have acted, and that it was thrown out unaltered in fragments of these rocks.

---

**Genus VIII. Sag.**

**Species 1. Emerald**

This stone has hitherto been only found crystallized. The primitive form of its crystals is a regular fixed prism; and the form of its integrant molecules is a triangular prism, whose sides are squares, and bases equilateral triangles. The most common variety of its crystals is the regular fixed prism, sometimes with the edges of the prism, or of the bases, or the solid angles, or both wanting, and small faces in their place. The sides of the prism are generally channelled.

Its texture is foliated. Its fracture conchoideal. Lustre usually from 3 to 4. Transparency from 2 to 4. Causes a double refraction. Hardness 12. Sp. gr. 2.65 to 2.775. Colour green. Becomes electric by friction, but not by heat. Its powder does not phosphoresce when thrown on a hot iron. At 130° Wedgewood it melts into an opaque coloured mass. According to Dolomieu, it is fusible per se by the blowpipe.

This mineral was formerly subdivided into two distinct species, the emerald, and beryl or aqua marina. Haüy demonstrated, that the emerald and beryl corresponded exactly in their structure and properties, and Vauquelin found that they were composed of the same ingredients; henceforth, therefore, they must be considered as varieties of the same species.

The variety formerly called emerald varies in colour from the pale to the perfect green. When heated to 120° Wedgewood, it becomes blue, but recovers its colour when cold. A specimen, analysed by Vauquelin, was composed of:

- 64.60 silica, - 14.00 alumina, - 13.00 glucina, - 3.50 oxyd of chromium, - 2.56 lime, - 2.00 moisture or other volatile ingredient.

---

The beryl is of a greyish green colour, and sometimes blue, yellow, and even white: sometimes different colours appear in the same stone. It is found in Ceylon, different parts of India, Brazil, and especially in Siberia and Tartary, where its crystals are sometimes a foot long. A specimen of beryl, analysed by Vauquelin, contained:

- 69 silica, - 13 alumina, - 16 glucina, - 1.5 oxyd of iron.

It was by analysing this stone that Vauquelin discovered the earth which he called glucina.

**Genus IX. 2ab.**

**Species 1. Staurolite.**

*Kirw. i.*

Androlite of Lametherie and Hauy—Hyacinthe blanche cruciforme, var. g. of Romé de Lisle.

This stone has been found at Andreasberg in the Harz. It is crystallized, and the form of its crystals has induced mineralogists to give it the name of cross-flane. Its crystals are two four-sided flattened prisms, terminated by four-sided pyramids, intersecting each other at right angles; the plane of intersection passing longitudinally through the prisms (1).

Its texture is foliated. Its lustre waxy, 2. Transparency from 1 to 3. Hardness 9. Brittle. Sp. gr. 2.355 to 2.361. Colour milk white. When heated slowly, it loses 0.15 or 0.16 parts of its weight, and falls into powder. It effervesces with borax and microcosmic salt, and is reduced to a greenish opaque mass. With soda it melts into a frothy white enamel. When its powder is thrown on a hot coal, it emits a greenish yellow light.

A specimen analysed by Wetzlum was composed of:

- 44 silica, - 20 alumina, - 20 barytes, - 16 water.

Klaproth found the same ingredients, and nearly in the same proportions.

A variety of staurolite has been found only once, which has the following peculiarities.

Its lustre is pearly, 2. Sp. gr. 2.361. Colour brownish grey. With soda it melts into a purplish and yellowish frothy enamel. It is composed, according to Wetzlum, of:

- 47.5 silica, - 12.0 alumina, - 20.0 barytes, - 16.0 water, - 4.5 oxyds of iron and manganese.

**Genus X. 1. ASL.**

**Species 1. Chrysoberyl.**

Oriental chrysoelite of jewellers—Cymopane of Hauy.

Hitherto this stone has been found only in Brazil, the island of Ceylon, and as some affirm near Novochinsk in Siberia. Werner first made it a distinct species, and gave it the name which we have adopted. It is usually found in round masses about the size of a pea, but it is sometimes also crystallized. The primitive form of its crystals is a four-sided rectangular prism, whose height is to its breadth as \( \sqrt{3} \) to 1, and to its thickness as \( \sqrt{2} \) to 1. The only variety hitherto observed is an eight-sided prism, terminated by six sided summits. Two of the faces of the prism are hexagons, two are rectangles, and four trapeziums; two faces of the summits are rectangles, and the other four trapeziums. Sometimes two of the edges of the prism are wanting, and small faces in their place.

Its texture is foliated. Laminæ parallel to the faces of the prism. Lustre 3 to 4. Transparency 3 to 4. Caused single refraction. Hardness 12. Sp. gr. from 3.698 to 3.796. Colour yellowish green, surface sparkling. It is infusible by the blow pipe per \( \frac{1}{2} \), and 1 hour with soda.

A specimen of chrysoberyl, analysed by Klaproth, was composed of:

- 71.5 alumina, - 18.0 silica, - 6.0 lime, - 1.5 oxyd of iron.

**Genus X. 2. SAL.**

**Species 2. Hyalite.**

This stone is frequently found in trap. It occurs in grains, filaments, and rhomboidal masses. Texture foliated. Fracture uneven, inclining to conchoïdal. Lustre glaify (m), 2 to 3. Transparency 2 to 3; sometimes, tho' seldom, it is opaque. Hardness 9. Sp. gr. 2.11. Colour pure white. Infusible at 150° Wedgwood; but it yields to soda. According to Mr Link, it is composed of:

- 57 silica, - 18 alumina, - 15 lime.

90 and a very little iron.

**Species 3. Edelte.**

This stone has hitherto been found only in Sweden at Mofleberg and Edelfors. From this last place Mr Kirwan, who first made it a distinct species, has given it the name which we have adopted. It was first mentioned by Bergman. Its form is tuberose and knotty. Texture striated; sometimes resembles quartz. Lustre from 0 to 1. Sp. gr. 2.515 after it has absorbed water. Colour light grey, often tinged red; also yellowish brown, yellowish green and green. Before the blow-pipe it intumesces and forms a frothy mass. Acids convert it into a jelly. A specimen from Mofleberg, analysed by Bergman, contained:

- 69 silica, - 20 alumina, - 8 lime, - 3 water.

A specimen from Edelfors yielded to the same effect:

- 62 silica, - 18 alumina, - 16 lime, - 4 water.

---

(l) See Gillot, *Jour. de Phys.* 1793, p. 1 and 2. (m) Hence probably the name hyalite, which was imposed by Werner from *varius glas*, and *aloe*, a stone. This stone was first described by Cronstedt in the Stockholm Transactions for 1756. It is found sometimes amorphous and sometimes crystallized. The primitive form of its crystals is a rectangular prism, whose bases are squares. The most common variety is a long four-sided prism, terminated by low four-sided pyramids.

Its texture is striated or fibrous. Its lustre is silky, from 3 to 4. Transparency from 2 to 4; sometimes 1. Hardness 6 to 8; sometimes only 4. Absorbs water. Sp. gr. 2.07 to 2.3. Colour white, often with a shade of red or yellow; sometimes brick red, green, blue. When heated, it becomes electric like the tourmaline. Before the blow-pipe it froths (o), emits a phosphorescent light, and melts into a white semitransparent enamel, too soft to cut glass, and soluble in acids. In acids it dissolves slowly and partially without effervescence; and at last, unless the quantity of liquid be too great, it is converted into a jelly.

A specimen of zeolite (v), analyzed by Vauquelin, contained:

- 53.00 silica, - 27.00 alumina, - 9.46 lime, - 10.00 water.

99.46%.

SPECIES 5. Stilbite.

This stone was first formed into a distinct species by Mr Hauy. Formerly it was considered as a variety of zeolite.

The primitive form of its crystals is a rectangular prism, whose bases are rectangles. It crystallizes sometimes in dodecahedrons, consisting of a four-sided prism with hexagonal faces, terminated by four-sided summits, whose faces are oblique parallelograms; sometimes in six-sided prisms, two of whose solid angles are wanting, and a small triangular face in their place.

Its texture is foliated. The laminae are easily separated from each other; and are somewhat flexible. Lustre nearly 2 or 3 (o). Hardness inferior to that of zeolite, which scratches stilbite. Brittle. Sp. gr. 2.500+. Colour pearl white. Powder bright white, sometimes with a shade of red. This powder, when exposed to the air, cakes and adheres as if it had absorbed water. It causes syrup of violets to assume a green colour. When stilbite is heated in a porcelain crucible, it swells up and assumes the colour and semitransparency of baked porcelain. By this process it loses 18% of its weight. Before the blow-pipe it froths like borax, and then melts into an opaque white coloured en-

According to the analysis of Vauquelin, it is composed of:

- 52.0 silica, - 17.5 alumina, - 9.0 lime, - 18.5 water.

97.0%

SPECIES 6. Analcime.

This stone, which was discovered by Mr Dolomieu, is found crystallized in the cavities of lava. It was first made a distinct species by Mr Hauy. Mineralogists had formerly confounded it with zeolite.

The primitive form of its crystals is a cube. It is sometimes found crystallized in cubes, whose solid angles are wanting, and three small triangular faces in place of each; sometimes in polyhedrons with 24 faces. It is usually somewhat transparent. Hardness about 8; scratches glass slightly. Sp. gr. above 2. When rubbed, it acquires only a small degree of electricity, and with difficulty (s). Before the blow-pipe it melts without frothing, into a white semitransparent glass.

GENUS X. 4. SLA.

SPECIES 7. Lazulite.

This stone, which is found chiefly in the northern parts of Asia, has been long known to mineralogists by the name of lazulite. This term has been contracted into lazulite by Mr Hauy; an alteration which was certainly proper, and which therefore we have adopted.

Lazulite is always amorphous. Its texture is earthy. Its fracture uneven. Lustre o. Opaque, or nearly so. Hardness 8 to 9. Sp. gr. 2.76 to 2.945+. Colour blue (s); often spotted white from specks of quartz, and yellow from particles of pyrites.

It retains its colour at 100° Wedgewood; in a higher heat it turns blue, and melts into a yellowish black mass. With acids it effervesces a little, and if previously calcined, forms with them a jelly.

Margraff published an analysis of lazulite in the Berlin Memoirs for 1758. His analysis has since been confirmed by Klaproth, who found a specimen of it to contain:

- 46.0 silica, - 14.5 alumina, - 29.0 carbonat of lime, - 6.5 sulphate of lime, - 3.0 oxyd of iron, - 2.0 water.

100.0%

GENUS XI. SALT.

SPECIES 1. Garnet.

This stone is found abundantly in many mountains. It is usually crystallized. The primitive form of its crystals

---

(n) Kirw. I. 278.—Guettard, IV. 637.—Bucquet, Mem. Sav. Etrang. IX. 576.—Pelletier, Jour. de Phys. XX. 420.

(o) Hence the name zeolite, given to this mineral by Cronstedt; from ζείν, to ferment, and λίθος, a stone.

(p) Dr Black was accustomed to mention, in the course of his lectures, that Dr Hutton had discovered soda in zeolite. This discovery has not hitherto been verified by any other chemical mineralogist.

(q) Hence the name given to this mineral by Hauy, stilbite, from στιλβος, to shine.

(r) Hence the name analcime given it by Hauy, from αναλκης, weak.

(s) Hence the name lazulite, from an Arabian word azul, which signifies blue.

(t) Kirw. I. 258.—Gerhard, Disquisitio physico-chymica Granatorium, &c.—Pasiniot, Jour. de Phys. III. 442.—Wurzleb, Ann. de Chim. L. 231. Mineralogy.

Beryl and crystals is a dodecahedron whose sides are rhombs, with angles of $78^\circ 31' 45''$ and $120^\circ 28' 16''$. The inclination of the rhombs to each other is $120^\circ$. This dodecahedron may be considered as a four-sided prism, terminated by four-sided pyramids. It is divisible into four parallelopipeds, whose sides are rhombs; and each half of these may be divided into four tetrahedrons, whose sides are isosceles triangles, equal and similar to either of the halves into which the rhomboidal faces of the dodecahedron are divided by their shorter diagonal. The integrant molecules of garnet are similar tetrahedrons.

Sometimes the edges of the dodecahedron are wanting, and small faces in their place; and sometimes garnet is crystallized in polyhedrons, having 24 trapezoidal faces.

For a description and figure of these, and other varieties of garnet, we refer to Romé de Lisle and Haüy.

The texture of garnet, as Bergman first showed, is foliated. Its fracture commonly conchoideal. Internal lustre from 4 to 2. Transparency from 2 to 4; sometimes only 1 or 2. Caules simple refraction. Hardness from 10 to 14. Sp. gr. 3.75 to 4.188. Colour usually red. Often attracted by the magnet. Fusible per se by the blow-pipe.

Variety 1. Oriental garnet (v).

Internal lustre 3 to 4. Transparency 4. Hardness 13 to 14. Sp. gr. 4 to 4.188. Colour deep red, inclining to violet (x).

Variety 2. Common garnet.

Fracture uneven, inclining to the conchoideal. Internal lustre 2 to 3. Transparency from 3 to 6. Hardness 10 to 11; sometimes only 9. Sp. gr. 3.75 to 4. Colour commonly deep red, inclining to violet; sometimes verging towards black or olive; sometimes leek green, brown, yellow.

Variety 3. Amorphous garnet.

Structure flatly. Lustre 2. Transparency 2 to 1. Hardness 11 to 12. Sp. gr. 3.89. Colour brownish or blackish red. Found in Sweden, Switzerland, and the East Indies.

A specimen of oriental garnet, analysed by Klaproth, contained:

- 35.73 silica, - 27.23 alumina, - 36.00 oxyd of iron, - 0.25 oxyd of manganese.

99.25

A specimen of red garnet, analysed by Vanquelin, contained:

- 52.0 silica, - 20.0 alumina, - 17.0 oxyd of iron, - 7.7 lime.

96.7

A specimen of black garnet yielded to the same chemist:

- 43.2 silica, - 16 alumina, - 20 lime, - 16 oxyd of iron, - 4 moisture.

99

Mr Klaproth found a specimen of Bohemian garnet, composed of:

- 40.00 silica, - 28.50 alumina, - 16.50 oxyd of iron, - 10.00 magnesia, - 3.50 lime, - 0.25 oxyd of manganese.

98.75

Species 2. Thumerstone.

Thumerstone of Lamethere—Asinute of Haüy.

This stone was first described by Mr Schreber, who found it near Balme d'Auris in Dauphiné, and gave it the name of florid violet. It was afterwards found near Thun in Saxony, in consequence of which Werner called it thumerstone.

It is sometimes amorphous; but more commonly crystallized. The primitive form of its crystals is a rectangular prism, whose bases are parallelograms with angles of $101^\circ 32'$ and $78^\circ 28'$. The most usual variety is a flat rhombohedral parallelopiped, with two of its opposite edges wanting, and a small face in place of each. The faces of the parallelopiped are generally streaked longitudinally.

The texture of thumerstone is foliated. Its fracture conchoideal. Lustre 2. Transparency, when crystallized, 3 to 4; when amorphous, 2 to 1. Caules simple refraction. Hardness 10 to 9. Sp. gr. 3.29; 6. Colour clove brown; sometimes inclining to red, green, grey, violet, or black. Before the blow-pipe it froths like zeolite, and melts into a hard black enamel. With borax it exhibits the same phenomena, or even when the stone is simply heated at the end of a pincer.

A specimen of thumerstone, analysed by Klaproth, contained:

- 52.7 silica, - 25.6 alumina, - 9.4 lime, - 9.6 oxyd of iron with a trace of manganese.

97.3

A specimen, analysed by Vanquelin, contained:

- 44 silica, - 18 alumina, - 19 lime, - 14 oxyd of iron, - 4 oxyd of manganese.

99

Species 3. Prehnite (y).

Though this stone had been mentioned by Sage, Romé de Lisle, and other mineralogists, Werner was the first who properly distinguished it from other minerals. He made it a distinct species. The specimen which he examined was brought from the Cape of Good Hope by Colonel Prehn; hence the name prehnite, by which he distinguished it. It was found near Dumbarton by Mr Groteche; and since that time it has been observed in other parts of Scotland.

(v) This seems to be the carbuncle (adject.) of Theophratus, and the carbunculus garamanticus of other ancient writers. See Hilp's Theophratus rerum naturalium, p. 74 and 77.

(x) Hence, according to many, the name garnet (in Latin granatus), from the resemblance of the stone in colour to the blossoms of the pomegranate.

(y) Kirw. I. 274.—Hassenfratz, Jour. de Phys. XXXII. 81.—Sage, ibid. XXXIV. 446.—Klaproth, Ber. der Berlin. Acad. 211. And Ann. de Chim. I. 201. It is both amorphous and crystallized. The crystals are in groups, and confused; they seem to be four-sided prisms with dihedral summits. Sometimes they are irregular six-sided plates, and sometimes flat rhombohedral parallelopipeds.

Its texture is foliated. Fracture uneven. Internal lustre pearly, scarcely 2. Transparency 3 to 2. Hardness 9 to 10. Brittle. Sp. gr. 2.6960. Colour apple green, or greenish grey. Before the blow-pipe it froths more violently than zeolite, and melts into a brown enamel. A specimen of prehnite, analysed by Klaproth, was composed of

\[ \begin{align*} 43.83 & \text{ silica}, \\ 30.33 & \text{ alumina}, \\ 18.43 & \text{ lime}, \\ 5.66 & \text{ oxyd of iron}, \\ 1.16 & \text{ air and water}. \end{align*} \]

Whereas Mr Hassenfratz found in another specimen

\[ \begin{align*} 50.0 & \text{ silica}, \\ 20.4 & \text{ alumina}, \\ 23.3 & \text{ lime}, \\ 4.9 & \text{ iron}, \\ .9 & \text{ water}, \\ .5 & \text{ magnesia}. \end{align*} \]

Species 4. Thallite.

Green flint of Dauphiné of De Lille — Delphinite of Sauflure.

This stone is found in the fissures of mountains; and hitherto only in Dauphiné and on Chamouni in the Alps. It is sometimes amorphous, and sometimes crystallized. The primitive form of its crystals is a rectangular prism, whose bases are rhombs with angles of 114° 37' and 65° 23'. The most usual variety is an elongated four-sided prism (often flattened), terminated by four-sided incomplete pyramids; sometimes it occurs in regular six-sided prisms. The crystals are often very slender.

Its texture appears fibrous. Lustre inconceivable. Transparency 2 to 3, sometimes 4; sometimes nearly opaque. Causes single refraction. Hardness 9 to 10. Brittle. Sp. gr. 3.4529 to 3.46. Colour dark green (a). Powder white or yellowish with green, and feels dry. It does not become electric by heat. Before the blow-pipe, froths and melts into a black fluid. With borax melts into a green bead.

A specimen of thallite, analysed by Mr Decurtins, contained

\[ \begin{align*} 37 & \text{ silica}, \\ 27 & \text{ alumina}, \\ 17 & \text{ oxyd of iron}, \\ 14 & \text{ lime}, \\ 1.5 & \text{ oxyd of manganese}. \end{align*} \]

Genus XII. 1. AMG.

Species 1. Cyanite.

Sapphire of Sauflure.

This stone was first described by Mr Sauflure, the O. XII. AMG., who gave it the name of sapphire. It is commonly found in granite rocks. The primitive form of its crystals is a four-sided oblique prism, whose sides are inclined at an angle of 103°. The base forms with one side of the prism an angle of 103°; with another, an angle of 77°. It is sometimes crystallized in six-sided prisms.

Its texture is foliated. Laminae long, splintery. Lustre pearly, 2 to 3. Transparency 3. Causes single refraction. Hardness 6 to 9. Brittle. Sp. gr. from 3.092 to 3.622. Feels rather greasy. Colour milk white, with shades of sky or prussian blue (a); sometimes bluish grey; sometimes partly bluish grey, partly yellowish or greenish grey.

Before the blow-pipe it becomes almost perfectly white; but does not melt. According to the analysis of Sauflure, it is composed of

\[ \begin{align*} 66.92 & \text{ alumina}, \\ 13.25 & \text{ magnesia}, \\ 12.81 & \text{ silica}, \\ 5.48 & \text{ iron}, \\ 1.71 & \text{ lime}. \end{align*} \]

Cyanite has also been analysed by Struvius and Hermann, who agree with Sauflure as to the ingredients; but differ widely from him and one another as to the proportions.

Struvius. Hermann.

\[ \begin{align*} 5.5 & - - - 30 \text{ alumina}, \\ 30.5 & - - - 39 \text{ magnesia}, \\ 54.5 & - - - 23 \text{ silica}, \\ 5.0 & - - - 2 \text{ iron}, \\ 4.0 & - - - 3 \text{ lime}. \end{align*} \]

Species 2. Serpentine.

This stone is found in amorphous masses. Its fracture is splintery. Lustre o. Opaline. Hardness 6 to 7. Sp. gr. 2.6665 to 2.700. Feels rather soft, almost greasy. Generally emits an earthy smell when breathed upon. Its colours are various shades of green, yellow, red, grey, brown, blue; commonly one or two colours form the ground, and one or more appear in spots or veins.

Before the blow-pipe it hardens and does not melt.

A specimen of serpentine, analysed by Mr Chenavix, contained

\[ \begin{align*} 34.3 & \text{ magnesia}, \\ 28.0 & \text{ silica}, \\ 23.0 & \text{ alumina}, \\ 4.5 & \text{ oxyd of iron}, \\ 0.5 & \text{ lime}, \\ 10.5 & \text{ water}. \end{align*} \]

(z) Hence the name thallite given it by Lametherie, from θάλασσα, a green leaf.

(a) Hence the name cyanite, imposed by Werner.

(b) Kirw. I. 156.—Margraf, Mem. Berlin, 1759, p. 3.—Bayen, Jour. de Phys. XIII. 46.—Mayer, Crell's Annals, 1789, II. 416.

(c) Hence the name serpentine, given to the stone from a supposed resemblance in colours to the skin of serpent. Genus XIII. MSAI.

Species 1. Pottstone†.

This stone is found in nests and beds, and is always amorphous. Its structure is often flaty. Texture undulatingly foliated. Lustre from 1 to 3. Transparency from 1 to 4; sometimes 2. Hardness 4 to 6. Brittle. Sp. gr. from 2.8531 to 3.023. Feels greasy. Sometimes absorbs water. Colour grey with a shade of green, and sometimes of red or yellow; sometimes leek green; sometimes speckled with red.

Pottstone is not much affected by fire; and has therefore been made into utensils for boiling water; hence its name.

According to Wieglob, the pottstone of Como contains:

- 38 magnesia, - 38 silica, - 7 alumina, - 5 iron, - 1 carbonat of lime, - 1 fluoric acid.

90

Species 2. Chlorite*.

This mineral enters as an ingredient into different mountains. It is sometimes amorphous, and sometimes crystallized in oblong, four-sided, acuminated crystals.

Its texture is foliated. Its lustre from 0 to 2. Opaque. Hardness from 4 to 6; sometimes in loose scales. Colour green.

Variety 1. Farinaceous chlorite.

Composed of scales scarcely cohering, either heaped together, or investing other stones. Feels greasy. Gives an earthy smell when breathed on. Difficult to pulverise. Colour greyish green; sometimes greenish brown; sometimes dark green, inclining to black. Streak white. When the powder of chlorite is exposed to the blowpipe it becomes brown. Before the blow pipe, farinaceous chlorite froths and melts into a dark brown glass; with borax it forms a greenish brown glass*.

Variety 2. Indurated chlorite.

This variety is crystallized. Lustre 1. Hardness 6. Feel meagre. Colour dark green, almost black. Streak mountain green.

Variety 3. Slaty chlorite.

Structure flaty. Fragments flattened. Internal lustre 1 to 2. Hardness 5. Colour greenish grey, or dark green inclining to black. Streak mountain green.

A specimen of the first variety, analysed by Vauquelin, contained:

- 43.3 oxyd of iron, - 26.0 silica, - 15.5 alumina, - 8.0 magnesia, - 2.0 muriat of potash, - 4.0 water.

98.8†

(d) Is this the tremolite of Lowitz from the lake Baikal in Siberia? If so, the name of the genus ought to be slem; for he found it to contain no alumina. According to his analysis, it was composed of:

- 52 silica, - 20 lime, - 12 carbonat of lime, - 12 magnesia,

96

A specimen of the same variety yielded Mr Hapner:

- 12.92 oxyd of iron, - 87.50 silica, - 4.17 alumina, - 43.75 magnesia, - 1.66 lime.

100.0‡

A specimen of the second variety, analysed by the same chemist, contained:

- 10.15 oxyd of iron, - 41.15 silica, - 6.13 alumina, - 39.47 magnesia, - 1.50 lime, - 1.50 air and water.

99.9§

On the supposition that these analyses are accurate, the enormous difference between them is a demonstration that chlorite is not a chemical combination, but a mechanical mixture.

Genus XIV. SLAM.

Species 1. Siliceous spar (p).

This stone has been found in Transylvania. It is crystallized in 4 or 6 sided prisms, channelled transversely, and generally heaped together. Its texture is fibrous. Its lustre silky, 2. Its colours white, yellow, green, light blue. According to Bindheim, it contains:

- 61.1 silica, - 21.7 lime, - 6.6 alumina, - 5.0 magnesia, - 1.3 oxyd of iron, - 3.3 water.

99.0*

Genus XV. SAMLI.

Species 1. Argillite†.

Argillaceous flintus—Common flate.

This stone constitutes a part of many mountains. Its structure is flaty. Its texture solid. Fracture splintery. Fragments often tabular. Lustre most commonly silky, 2; sometimes 0. Transparency from 0 to 1. Hardness from 5 to 8. Sp. gr. from 2.67 to 2.88. Does not adhere to the tongue. Gives a clear sound when struck. Often imbibes water. Streak white or grey. Colour most commonly grey, with a shade of blue, green, or black; sometimes purplish, yellowish, mountain green, brown, bluish black; sometimes striped or spotted with a darker colour than the ground.

It is composed, according to Kirwan, of silica, alumina, magnesia, lime, oxyd of iron. In some varieties the Genus XVI. Smaragdite.

Species 1. Smaragdite.

This stone was called smaragdite by Mr Smith, from some resemblance which it has to the emerald. Its texture is foliated. The laminae are inflexible. Fracture even. Hardness 7. Colour in some cases fine green; in others it has the grey colour and metallic lustre of mica: it assumes all the shades of colour between these two extremes.

According to the analysis of Vauquelin, it is composed of:

- 50.0 silica, - 13.0 lime, - 11.0 alumina, - 7.5 oxyd of chromium, - 6.0 magnesia, - 5.5 oxyd of iron, - 1.5 oxyd of copper.

94.5

Genus XVII. Myrten.

Species 1. Kiftekit.

Myrten—Seafoam.

This mineral is dug up near Konig in Natolia, and is employed in forming the bowls of Turkish tobacco pipes. The sale of it supports a large monastery of dervishes established near the place where it is dug. It is found in a large fissure five feet wide, in grey calcareous earth. The workmen assert, that it grows again in the fissure, and puts itself up like froth (x). This mineral, when fresh dug, is of the consistence of wax; it feels soft and greasy; its colour is yellow; its sp. gr. 1.660; when thrown on the fire it swells, emits a fetid vapour, becomes hard, and perfectly white.

According to the analysis of Klaproth, it is composed of:

- 50.50 silica, - 17.25 magnesia, - 25.00 water, - 5.00 carbonic acid, - 1.50 lime.

98.25

Species 2. Steatites (v).

Though this mineral was noticed by the ancients, little attention was paid to it by mineralogists, till Mr Pott published his experiments on it in the Berlin Memoirs for 1747.

It is usually amorphous, but sometimes it is crystallized in six-sided prisms. Its texture is commonly earthy, but sometimes foliated. Lustre from o to 1. Transparency from o to 2. Hardness 4 to 7. Sp. gr. from 2.61 to 2.794. Feels greasy. Seldom adheres to the tongue. Colour usually white or grey; often with a tint of other colours; the foliated commonly green. Does not melt per se before the blow-pipe.

Variety 1. Semi-indurated steatites.

Texture earthy. Fracture sometimes coarse splintery. Lustre o. Transparency 2, or scarce 1. Hardness 4 to 5. Absorbs water. Takes a polish from the nail. Colour white, with a shade of grey, yellow, or green; sometimes pure white; sometimes it contains dendritic figures; and sometimes red veins.

Variety 2. Indurated steatites.

Fracture fine splintery, often mixed with imperfectly conchoidal. External lustre 2 to 1, internal o. Transparency 2. Often has the feel of soap. Absorbs water. Colour yellowish or greenish grey; often veined or spotted with deep yellow or red.

Variety 3. Foliated or striated steatites.

The texture of this variety is usually foliated; sometimes striated. Fragments cubiform. Lustre 3. Transparency 2 to 1. Hardness 6 to 7. Colour leek green, passing into mountain green or sulphur yellow. Streak pale greenish grey. When heated to redness, it becomes grey; and at 1470 Wedgwood, it forms a grey porous porcelain mass.

A specimen of steatites, analysed by Klaproth, contained:

- 59.5 silica, - 30.5 magnesia, - 2.5 iron, - 5.5 water.

98.0

A specimen of white steatites, analysed by Mr Chevallier, contained:

- 60.00 silica, - 28.50 magnesia, - 3.00 alumina, - 2.50 lime, - 2.25 iron.

96.25

Genus XVIII. Chrysolite (g).

Period of the French—Topaz of the ancients.

The name chrysolite was applied, without discrimination, to a great variety of stones, till Werner defined it accurately, and confined it to that stone which the French chemists distinguished by the appellation of peridot. This stone is the topaz of the ancients; their chrysolite is now called topaz (g).

Chrysolite is found sometimes in unequal fragments, and sometimes crystallized. The primitive form of its crystals is a right angled parallelopiped, whose length, breadth, and thickness, are as \( \sqrt{3} : \sqrt{8} : \sqrt{5} \).

The texture of the chrysolite is foliated. Its fracture conchoidal. Its internal lustre from 2 to 4. Its Min. N° transparency from 4 to 2. Causes double refraction.

The carbonat of lime was only mechanically interposed between the fibres of the stone. See Pallas, Neu. Nord. Beitrage, 6 Band, p. 146.

(x) Hence the name kiftekit, or rather kifte-kelli, "clay froth," or "light clay."

(y) Kirw. I. 151.—Pott, Mem. Berlin, 1747, p. 57.—Wiegled, Jour. de Phys. XXIX. 60.—Lavoisier, Mem. Par. 1778, 433.

(z) Kirw. I. 262.—Carstenfer, Min. 94.—Dolomieu, Jour. de Min. No xxix. 365.—La Mettrie, Nouv. Jour. de Phys. I. 397. This mineral was well known to the ancients. They even made a kind of cloth from one of the varieties, which was famous among them for its incombatibility. It is found abundantly in most mountainous countries, and nowhere more abundantly than in Scotland.

It is commonly amorphous. Its texture is fibrous. Its fragments often long splintery. Luster from 0 to 2; sometimes 3, and then it is metallic. Transparency from 0 to 2. Hardness from 3 to 7. Sp. gr. from 2.7 to 6.866. Absorbs water. Colour usually white or green. Fusible per se by the blow-pipe.

**Variety 1.** Common asbestos.

Luster 2 to 4. Transparency 1. Hardness 6 to 7. Sp. gr. 2.577 to 2.7. Feels somewhat greasy. Colour leek green; sometimes olive or mountain green; sometimes greenish or yellowish grey. Streak grey. Powder grey.

**Variety 2.** Flexible asbestos.

**Amiantus.**

Composed of a bundle of threads slightly cohering. Fibres flexible. Luster 1 to 2, sometimes 3. Transparency 1 to 2, sometimes 3. Hardness 3 to 4. Sp. gr. before it absorbs water, from 0.9088 to 2.3134; after absorbing water, from 1.6662 to 2.3829. Feels greasy. Colour greyish or greenish white; sometimes yellowish or silvery white, olive or mountain green, pale leek red, and mountain yellow.

**Variety 3.** Elastic asbestos.

**Mountain cork.**

This variety has a strong resemblance to common cork. Its fibres are interwoven. Luster commonly 0. Opaque. Hardness 4. Sp. gr. before absorbing water, from 0.6806 to 0.9933; after absorbing water, from 1.2492 to 1.3492. Feels meagre. Yields to the fingers like cork, and is somewhat elastic. Colour white; sometimes with a shade of red or yellow; sometimes yellow or brown.

A specimen of the first variety from Dalecarlia, analyzed by Bergman, contained:

- 63.9 silica, - 16.0 carbonat of magnesia, - 12.8 carbonat of lime, - 6.0 oxyd of iron, - 1.1 alumina.

99.8

A specimen of the second variety yielded to the same chemist:

- 64.0 silica, - 17.2 carbonat of magnesia, - 13.9 carbonat of lime, - 2.7 alumina, - 2.2 oxyd of iron.

100.0

A specimen of the third variety contained, according to the same analysis:

- 56.2 silica, - 26.1 carbonat of magnesia, - 12.7 carbonat of lime, - 3.0 iron, - 2.2 alumina.

100.0

---

(h) Kirw. I. 171.—Bartolin, De Lapide Nephritico.—Lehmann, Nov. Comm. Petropol. X. 381.—Hoffner, Hist. Nat. de la Suisse, I. 251.

(i) Kirw. I. 159.—Bergman, IV. 160.—Plot, Phil. Trans. XV. 1051.—Nebel, Jour. de Phys. II. 62.—Ibid. III. 367. **Genus XX. 2. Smil.**

**Species 3.** Shortaceous actinolite (m).

This stone crystallizes in four or six sided prisms, thicker at one end than the other; hence it has been called by the Germans *fläbelfeim*, "arrow-stone." The crystals sometimes adhere longitudinally. Fracture actinolite hackly. External lustre glassy, 3 to 4; internal, 1 to 2. Transparency from 2 to 3; sometimes 1. Hardness from 7 to 10. Sp. gr. 3.023 to 3.45. Colour leek or dark green.

This stone is often the matrix of iron, copper, and tin ores.

**Species 5.** Lamellar actinolite.

This stone resembles hornblende. It is amorphous actinolite. Texture foliated. Lustre various in different places. Transparency 0, or scarce 1. Sp. gr. 2.916. Colour dark yellowish or greenish grey.

**Species 6.** Glassy actinolite.

This stone is found amorphous, composed of fibres actinolite, adhering longitudinally, or in slender four or six sided prisms. Texture fibrous. Fragments long splintery, so sharp that they can scarcely be handled without injury. External lustre glassy or silky, 3 to 4; internal 0. Transparency 2. Exceedingly brittle. Sp. gr. 2.95 to 3.493. Colour leek green; sometimes verging towards greenish or silver white; sometimes flamed with yellowish or brownish red. According to Bergman it is composed of 72.0 silica, 12.7 carbonat of magnesia, 6.0 carbonat of lime, 7.0 oxyd of iron, 2.0 alumina.

---

**Genus XXI. 3.**

**Species 1.** Shitfoe hornstone +.

The structure of this stone is flaky. Lustre from 0 to 1. Commonly opaque. Hardness 9 to 10. Sp. gr. from 2.596 to 2.641. Colour dark bluish or blackish grey. Insoluble per se.

**Variety 1.** Siliceous flint.

Commonly intersected by reddish veins of iron stone. Fracture splintery. Lustre 0. Transparency from 0 to 1.

**Variety 2.** Bafanite or Lydian stone.

Commonly intersected by veins of quartz. Fracture even; sometimes inclining to conchoidal. Lustre scarce 1. Hardness 10. Sp. gr. 2.596. Powder black. Colour greyish black.

This, or a stone similar to it, was used by the ancients as a touchstone. They drew the metal to be examined along the stone, and judged of its purity by the

---

(k) Kirw. Min. I. 165. Is this the tremolite of Werner? It certainly is not the tremolite of the French mineralogists.

(l) Hence the name pyroen given it by Haug; from *pyr* fire, and *eun* a stranger. It means, as he himself explains it, a stranger in the regions of fire. By this he means to indicate, that pyroxen, though present in lava, is not a volcanic production.

(m) In this and the following species we have followed Mr Kirwan's new arrangement exactly, without even venturing to give the synonyms of other authors. The descriptions which have been given are too many and incomplete, and the minerals themselves are still so imperfectly known, and have got so many names, that no part of mineralogy is in a state of greater confusion. Earth and the colour of the metallic streak. On this account they called it *baracite*, the tricr. They called it also *Lydian stone*, because, as Theophrastus informs us, it was found most abundantly in the river Tmolus in Lydia.

A specimen of the first variety, analysed by Wieg- leb, contained:

- 75.0 silica, - 10.0 lime, - 4.6 magnesia, - 3.5 iron, - 5.2 carbon.

This species is rather a mechanical mixture than a chemical combination.

**GENUS XXII.**

**SPECIES I. Zircon.**

*Jargon—Hyacinth.*

This stone is brought from Ceylon, and found also in France, Spain, and other parts of Europe. It is commonly crystallized. The primitive form of its crystals is an octahedron, composed of two four sided pyramids applied base to base, whose sides are isosceles triangles (n). The inclination of the sides of the same pyramid to each other is $120^\circ$; the inclination of the sides of one pyramid to those of another $82^\circ 50'$. The solid angle at the apex is $73^\circ 44'$. The varieties of the crystalline forms of zircon amount to seven. In some cases there is a four sided prism interposed between the pyramids of the primitive form; sometimes all the angles of this prism are wanting, and two small triangular faces in place of each; sometimes the crystals are dodecahedrons, composed of a flat four sided prism with hexagonal faces, terminated by four sided summits with rhomboidal faces; sometimes the edges of this prism, sometimes the edges where the prism and summit join, and sometimes both together, are wanting, and we find small faces in their place. For an accurate description and figure of these varieties, we refer to Mr. Haury.

The texture of the zircon is foliated. Internal lustre 3. Transparency from 4 to 2. Causes a very great double refraction. Hardness from 10 to 16. Sp. gr. from 4.2 to 4.65+. Colour commonly reddish or yellowish; sometimes it is limpid.

Before the blow pipe it loses its colour, but not its transparency. With borax it melts into a transparent glass. Infusible with fixed alkali and microcosmic salt.

1. The variety formerly called hyacinth is of a yellowish red colour, mixed with brown. Its surface is smooth. Its lustre 3. Its transparency 3 to 4.

2. The variety formerly called jargon of Ceylon, is either grey, greenish, yellowish brown, reddish brown, or violet. It has little external lustre. Is sometimes nearly opaque.

The first variety, according to the analysis of Vauquelin, is composed of:

- 64.5 zirconia, - 32.0 silica, - 2.0 oxyd of iron.

98.5+

A specimen analysed by Klaproth contained:

- 70.0 zirconia, - 25.0 silica, - 0.5 oxyd of iron.

95.5+

The second variety, according to Klaproth, who discovered the component parts of both these stones, contains:

- 68.0 zirconia, - 31.5 silica, - 0.5 nickel and iron.

100.0

**ORDER II. SALINE STONES.**

Under this order we comprehend all the minerals which consist of an earthy basis combined with an acid. They naturally divide themselves into five genera. We shall describe them in the following order.

I. **CALCAREOUS SALTS.** - Carbonat of lime, - Sulphat of lime, - Phosphat of lime, - Flust of lime, - Borat of lime.

II. **BARYTIC SALTS.** - Carbonat of barytes, - Sulphat of barytes.

III. **STRONTITIC SALTS.** - Carbonat of strontites, - Sulphat of strontites.

IV. **MAGNESIAN SALTS.** - Sulphat of magnesia.

V. **ALUMINOUS SALTS.** - Alum.

**GENUS I. CALCAREOUS SALTS.**

This genus comprehends all the combinations of lime and acids which form a part of the mineral kingdom.

**SPECIES I. Carbonat of lime.**

No other mineral can be compared with carbonat of lime in the abundance with which it is scattered over the earth. Many mountains consist of it entirely, and hardly a country is to be found on the face of the globe where, under the names of limestone, chalk, marble, spar, it does not constitute a greater or smaller part of the mineral riches.

It is often amorphous, often stalactitical, and often crystallized. The primitive form of its crystals is a paralleloiped, whose sides are rhombs, with angles of $77^\circ 30'$ and $102^\circ 30'$. Its integrant molecules have the same form. The varieties of its crystals amount to more than 40; for a description and figure of which we refer to Rome de Lisle and Haury (o).

When crystallized, its texture is foliated; when amorphous, its structure is sometimes foliated, sometimes fibrous, sometimes granular, and sometimes earthy. Its lustre

---

(n) Let ABC (fig. 27.) be one of the sides. Draw the perpendicular BD; then AB = 5, BD = 4, AD = 3.

(o) Effai d'une Theorie, &c. p. 75.—Jour. de Phys. 1793, August, p. 114.—Jour. d'Hist. Nat. 1792, February, p. 148.—Ann. de Chim. XVII. 249. &c.—Jour de Min. No XXVIII. 304. Order II.

It causes double refraction; and it is the only mineral which causes double refraction through two parallel faces of the crystal. Hardness from 3 to 9. Sp. gr. from 2.315 to 2.78. Colour, when pure, white. Effervesces violently with muriatic acid, and dissolves completely, or leaves but a small residuum. The solution is colourless.

This species occurs in a great variety of forms; and therefore has been subdivided into numerous varieties. All these may be conveniently arranged under two general divisions:

I. Soft carbonat of lime.

Variety 1. Agaric mineral.

Mountain milk, or mountain meal of the Germans. This variety is found in the clefts of rocks, or the bottom of lakes. It is nearly in the state of powder; of a white colour, sometimes with a shade of yellow; and so light, that it almost floats on water.

Variety 2. Chalk.

The colour of chalk is white, sometimes with a shade of yellow. Lustre o. Opaque. Hardness 3 to 4. Sp. gr. from 2.315 to 2.657. Texture earthy. Adheres slightly to the tongue. Feels dry. Stains the fingers, and marks. Falls to powder in water. It generally contains about 1/2 of alumina, and 1/2 of water; the rest is carbonat of lime.

Variety 3. Arenaceous limestone.

Colour yellowish white. Lustre 1. Transparency 1. So brittle, that small pieces crumble to powder between the fingers. Sp. gr. 2.712. Phosphoresces in the dark when scraped with a knife, but not when heated. It consists almost entirely of pure carbonat of lime.

II. Indurated carbonat of lime.

Variety 1. Compact limestone.

The texture of this variety is compact. It has little lustre; and is most commonly opaque. Hardness 5 to 8. Sp. gr. 1.3864 to 2.72. Colour grey, with various shades of other colours. It most commonly contains about 1/2 of alumina, oxyd of iron, &c.; the rest is carbonat of lime. This variety is usually burnt as lime.

Variety 2. Granularly foliated limestone.

Structure sometimes flaky. Texture foliated and granular. Lustre 2 to 1. Transparency 2 to 1. Hardness 7 to 8. Sp. gr. 2.71 to 2.8376. Colour white, of various shades from other colours.

Variety 3. Sparry limestone.

Structure sparry. Texture foliated. Fragments rhomboidal. Lustre 2 to 3. Transparency from 2 to 4; sometimes 1. Hardness 5 to 6. Sp. gr. from 2.693 to 2.718. Colour white; often with various shades of other colours. To this variety belong all the crystals of carbonat of lime.

Variety 4. Striated limestone.

Texture striated or fibrous. Lustre 1 to 0. Transparency 2 to 1. Hardness 5 to 7. Sp. gr. commonly from 2.6 to 2.77. Colours various.

Variety 5. Swine stone.

Texture often earthy. Fracture often splintery. Lustre 1 to 0. Transparency 0 to 1. Hardness 6 to 7. Sp. gr. 2.701 to 2.7121. Colour dark grey, of various shades. When scraped or pounded, it emits an urinous or garlic smell.

Variety 6. Oviform.

This variety consists of a number of small round bodies, closely compacted together. Lustre o. Transparency 0 or 1. Hardness 6 to 7.

SPECIES 2. Sulphat of lime.

Gypsum—Selenite.

This mineral is found abundantly in Germany, France, England, Italy, &c.

It is found sometimes in amorphous masses, sometimes in powder, and sometimes crystallized. The primitive form of its crystals, according to Romé de Lisle, is a decahedron +, which may be conceived as two four-sided pyramids, applied base to base, and which, instead of terminating in pointed summits, are truncated near their bases; so that the sides of the pyramids are trapeziums, and they terminate each in a rhomb. These rhombs are the largest faces of the crystal. The angles of the rhombs are 120° and 150°. The inclination of two opposite faces of one pyramid to the two similar faces of the other pyramid is 145°; that of the other faces 110°. Sometimes some of the faces are elongated; sometimes it crystallizes in fixed-sided prisms, terminated by three or four sided summits, or by an indeterminate number of curvilinear faces. For a description and figure of these varieties, we refer to Romé de Lisle.

The texture of sulphat of lime is most commonly foliated. Lustre from 0 to 4. Transparency from 0 to 4. It causes double refraction. Its hardness does not exceed 4. Its sp. gr. from 1.872 to 2.311. Colour commonly white or grey.

Before the blow-pipe, it melts into a white enamel, provided the blue flame be made to play upon the edges of its laminae. When the flame is directed against its faces, the mineral falls into powder.

It does not effervesce with muriatic acid, except it be impure; and it does not dissolve in it.

The following varieties of this mineral are deserving of attention.

Variety 1. Broad foliated sulphat.

Texture broad foliated. Lustre glassy, from 4 to 2. Transparency from 4 to 3. Hardness 4. Sp. gr. 2.311. Colour grey, often with a shade of yellow.

Variety 2. Grano-foliated sulphat.

Texture foliated, and at the same time granular; so that it easily crumbles into powder. Lustre 2 to 3. Transparency 2 to 3. Hardness 4 to 3. Sp. gr. from 2.274 to 2.310. Feels soft. Colour white or grey, often with a tinge of yellow, blue, or green; sometimes flesh red, brown, or olive green.

Variety 3. Fibrous sulphat.

Texture fibrous. Fragments long splintery. Lustre 2 to 3. Transparency 2 to 1; sometimes 3. Hardness 4. Brittle. Sp. gr. 2.300. Colour white, often with a shade of grey, yellow, or red; sometimes flesh red, and sometimes honey yellow; sometimes several of these colours meet in stripes.

Variety 4. Compact sulphat.

Texture compact. Lustre 1 or 0. Transparency 2 to 1.

SPECIES 1. Phosphat of lime.

Apatite—Phosphorite—Chrysolite—of the French.

This substance is found in Spain, where it forms whole mountains, and in different parts of Germany. It is sometimes amorphous, and sometimes crystallized. The primitive form of its crystals is a regular six-sided prism. Its integrant molecule is a regular triangular prism, whose height is to a side of its base as 1 to √2. Sometimes the edges of the primitive hexagonal prism are wanting, and small faces in their place; sometimes there are small faces instead of the edges which terminate the prism; sometimes these two varieties are united; sometimes the terminating edges and the angles of the prism are replaced by small faces; and sometimes the prism is terminated by four sided pyramids.

Its texture is foliated. Its fracture uneven, tending to conchoidal. External lustre from 2 to 3; internal 3 to 2. Transparency from 4 to 2. Causes single refraction. Hardness 6 to 7. Brittle. Sp. gr. from 2.8249 to 3.218. Colour commonly green or grey; sometimes brown, red, blue, and even purple.

It is fusible by the blow-pipe. When its powder is thrown upon burning coals, it emits a yellowish green phosphorescent light. It is soluble in muriatic acid without effervescence or decomposition, and the solution often becomes gelatinous.

SPECIES 2. Fluit of lime.

Fluor.

This mineral is found abundantly in different countries, particularly in Derbyshire. It is both amorphous and crystallized.

The primitive form of its crystals is the regular octahedron; that of its integrant molecules the regular tetrahedron. The varieties of its crystals hitherto observed amount to 7. These are the primitive octahedron; the cube; the rhombohedral dodecahedron; the cubo-octahedron, which has both the faces of the cube and of the octahedron; the octahedron wanting the edges; the cube wanting the edges, and either one face, or two faces in place of each. For a description and figure of these we refer to Mr. Haug.

The texture of fluit of lime is foliated. Lustre from 2 to 3, sometimes 5. Transparency from 2 to 4, sometimes 1. Causes single refraction. Hardness 8. Very brittle. Sp. gr. from 3.0943 to 3.1011. Colours numerous, red, violet, green, red-yellow, blackish purple. Its powder thrown upon hot coals emits a bluish or greenish light. Two pieces of it rubbed in the dark phosphoresce. It decrepitates when heated. Before the blow-pipe it melts into a transparent glass.

It admits of a polish, and is often formed into vases and other ornaments.

SPECIES 3. Potat of lime.

Boracite.

This mineral has been found at Kalkberg near Luneburg, seated in a bed of sulphate of lime. It is crystallized. The primitive form of its crystals is the cube. In general, all the edges and angles of the cube are truncated; sometimes, however, only the alternate angles are truncated. The size of the crystals does not exceed half an inch.

The texture of this mineral is compact. Its fracture is flat conchoidal. External lustre 3; internal, greasy. Transparency from 2 to 3. Hardness 9 to 10. Sp. gr. 2.666. Colour greyish white, sometimes palping into greenish white or purplish.

When heated it becomes electric; and the angles of the cube are alternately positive and negative.

Before the blow-pipe it froths, emits a greenish light, and is converted into a yellowish enamel, garnished with small points, which, if the heat be continued, dart out in sparks.

According to Wetzler, who discovered its component parts, it contains:

- 68 boracic acid, - 13.5 magnesia, - 11 lime, - 1 alumina, - 2 silica, - 1 iron.

SPECIES 4. Nitrat of lime.

Found abundantly mixed with native nitre. For a description see the article Chemistry in this Supplement, p. 672.

GENUS II. BARYTIC SALTS.

This genus comprehends the combinations of barytes with acids.

SPECIES 1. Carbonat of barytes.

Witherite.

This mineral was discovered by Dr. Withering; hence Werner has given it the name of witherite. It is found both amorphous and crystallized. The crystals are octahedrons or dodecahedrons, consisting of four or six sided pyramids applied base to base; sometimes the six sided pyramids are separated by a prism; sometimes several of these prisms are joined together in the form of a star.

Its texture is fibrous. Its fracture conchoidal. Its fragments long splintery. Lustre 2. Transparency 2 to 3. Hardness 5 to 6. Brittle. Sp. gr. 4.3 to 4.338. Colour greenish white. When heated it becomes opaque. Its powder phosphoresces when thrown on burning coals.

It is insoluble with effervescence in muriatic acid. The solution is colourless.

According to Pelletier it contains:

- 62 barytes, - 22 carbonic acid, - 16 water.

100+

SPECIES 2. Sulphat of barytes.

Borofelinite.

This mineral is found abundantly in many countries, particularly in Britain. It is sometimes in powdery, often in amorphous masses, and often crystallized. The primitive form of its crystals is a rectangular prism, whole

The varieties of its crystals are very numerous. For a description and figure of them we refer to René de Laffitte and Haüy*. The most common varieties are the octahedron with cuneiform summits, the six or four-sided prism, the hexagonal table with bevelled edges. Sometimes these crystals are needle form. Its texture is commonly foliated. Lustre from 0 to 2. Transparency from 2 to 3; in some cases 3 or 4. Hardness from 5 to 6. Sp. gr. from 4.4 to 4.44. Colour commonly white, with a shade of yellow, red, blue, or brown.

When heated it decrepitates. It is fusible per se by the blue flame of the blow-pipe, and is converted into sulphur of barytes. Soluble in no acid except the sulphuric; and precipitated from it by water.

Variety 1. Foliated sulphate.

Lustre 3 to 3. Transparency from 4 to 2, sometimes 1. Colours white, reddish, bluish, yellowish, blackish, greenish. Mr Werner subdivides this variety into three, according to the nature of the texture. These three subdivisions are granularly foliated, straight foliated, curved foliated.

Variety 2. Fibrous sulphate.

Texture fibrous; fibres converging to a common centre. Lustre silky or waxy. Transparency 2 to 1. Hardness 5. Colours yellowish, bluish, reddish.

Variety 3. Compact sulphate.

Texture compact. Lustre 0 to 1. Transparency 1 to 0. Feels meagre. Almost constantly impure. Colours light yellow, red, or blue.

Variety 4. Earthy sulphate.

In the form of coarse dusty particles, slightly cohering. Colour reddish or yellowish white.

GENUS III. STRONTITIC SALTS.

This genus comprehends all the combinations of strontites and acids which form a part of the mineral kingdom.

Species 1. Carbonat of strontites.

This mineral was first discovered in the lead mine of Strontion in Argyleshire; and since that time it is said to have been discovered, though not in great abundance, in other countries. It is found amorphous, and also crystallized in needles, which, according to Haüy, are regularly six sided prisms.

Its texture is fibrous; the fibres converge. Fracture uneven. Lustre 2. Transparency 2. Hardness 5. Sp. gr. from 3.4 to 3.66. Colour light green. Does not decrepitate when heated. Before the blow pipe becomes opaque and white, but does not melt. With borax it effervesces, and melts into a transparent colourless glass. Effervesces with muriatic acid, and is totally dissolved. The solution tinges flame purple.

Species 2. Sulphat of strontites.

Celestine.

This mineral has been found in Pennsylvania, in Germany, in France, in Sicily, and Britain. It was first discovered near Bristol by Mr Clayfield. There it is found in such abundance, that it has been employed in mending the roads.

It occurs both amorphous and crystallized. The crystals are most commonly bevelled tables, sometimes rhomboidal cubes. Its texture is foliated. More or less transparent. Hardness 5. Sp. gr. from 3.57 to Aggregates 3.96. Colour most commonly a fine sky blue; sometimes reddish; sometimes white, or nearly colourless.

Klaproth found a specimen of this mineral from Pennsylvania composed of 58 strontites, 42 sulphuric acid.

According to the analysis of Mr Clayfield, the sulphat of strontites found near Bristol is composed of 58.25 strontites, 41.75 sulphuric acid of 2.24, and a little iron.

According to the analysis of Vanquelin, the sulphat of strontites found at Bouvron in France, which was contaminated with .1 of carbonat of lime, is composed of 54 strontites, 45 sulphuric acid.

GENUS IV. MAGNESIAN SALTS.

This genus comprehends the combinations of magnesia and acids which occur in the mineral kingdom. Only two species have hitherto been found; namely,

Species 1. Sulphat of magnesia.

It is found in Spain, Bohemia, Britain, &c.; and magnesia enters into the composition of many mineral waters. For a description of it, we refer to Chemistry, n° 633, in this Suppl.

Species 2. Nitrat of magnesia.

Found sometimes associated with nitre. For a description see Chemistry, n° 674.

GENUS V. ALUMINOUS SALTS.

This genus comprehends those combinations of alumino-magnesia and acids which occur in the mineral kingdom.

Species 1. Alum.

This salt is found in crystals, in soft masses, in flakes, and invisibly mixed with the soil. For a description, we refer to Chemistry, n° 636.

ORDER III. AGGREGATES.

This order comprehends all mechanical mixtures of earths and stones found in the mineral kingdom. These are exceedingly numerous: the mountains and hills, the mould on which vegetables grow, and indeed the greater part of the globe, may be considered as composed of them. A complete description of aggregates belongs rather to geology than mineralogy. It would be improper, therefore, to treat of them fully here. But they cannot be altogether omitted; because aggregates are the first substances which present themselves to the view of the practical mineralogist, and because, without being acquainted with the names and component parts of many of them, the most valuable geological works could not be undertaken.

Aggregates may be comprehended under four divisions:

1. Mixtures of earths; 2. Amorphous fragments of stones agglutinated together; 3. Crystallized stones, either agglutinated together or with amorphous stones; 4. Aggregates formed by fire. It will be exceedingly convenient... Earth and convenient to treat each of these separately. We shall therefore divide this order into four sections.

**Sect. I. Aggregates of Earths.**

The most common earthy aggregates may be comprehended under the following genera:

1. Clay, 2. Colorific earths, 3. Marl, 4. Mould.

**Genus I. CLAY.**

Clay is a mixture of alumina and silica in various proportions. The alumina is in a state of an impalpable powder; but the silica is almost always in small stones, large enough to be distinguished by the eye. Clay, therefore, exhibits the character of alumina, and not of silica, even when this last ingredient predominates. The particles of silica are already combined with each other; and they have so strong an affinity for each other, that few bodies can separate them; whereas the alumina, not being combined, readily displays the characters which distinguish it from other bodies. Besides alumina and silica, clay often contains carbonat of lime, of magnesia, barytes, oxyd of iron, &c. And as clay is merely a mechanical mixture, the proportion of its ingredients is exceedingly various.

Clay has been divided into the following species:

**Species 1. Porcelain clay.**

Its texture is earthy. Its lustre o. Opaque. Hardness 4. Sp. gr. from 2.23 to 2.4. Colour white, sometimes with a shade of yellow or red. Adheres slightly to the tongue. Feels soft. Falls to powder in water.

A specimen, analysed by Hassenfratz, contained

- 62 silica, - 19 alumina, - 12 magnesia, - 7 sulphate of barytes.

**Species 2. Common clay.**

Its texture is earthy. Lustre o. Opaque. Hardness 3 to 6. Sp. gr. 1.8 to 2.68. Adheres slightly to the tongue. Often feels greasy. Falls to powder in water. Colour, when pure, white; often tinged blue or yellow.

**Variety 1. Potter's clay.**

Hardness 3 to 4. Sp. gr. 1.8 to 2. Stains the fingers slightly. Acquires some polish by friction. Colour white; often with a tinge of yellow or blue; sometimes brownish, greenish, reddish. Totally diffusible in water; and, when duly moistened, very ductile.

**Variety 2. Indurated clay.**

Hardness 5 to 6. Does not diffuse itself in water, but falls to powder. Discovers but little ductility. Colours grey, yellowish, bluish, greenish, reddish, brownish.

**Species 3. Shiltose clay.**

Structure flaky. Sp. gr. from 2.6 to 2.68. Feels smooth. Streak white or grey. Colour commonly bluish, or yellowish-grey; sometimes blackish, reddish, greenish. Found in strata, usually in coal mines.

This variety is sometimes impregnated with bitumen. It is then called bituminous shale.

**Species 3. Lithomarga.**

Texture earthy. Fracture conchoidal. Lustre from 3 to 4. Opaque. Hardness 3 to 7. Sp. gr. when pretty hard, 2.815. Surface smooth, and feels foamy. Adheres strongly to the tongue. Falls to pieces, and then to powder; in water; but does not diffuse itself through that liquid. Fulfible per se into a frothy mass.

**Variety 1. Friable lithomarga.**

Formed of fleshy particles slightly cohering. Lustre 1 to 2. Hardness 3 to 4. Exceedingly light. Feels very smooth, and affumes a polish from the nail. Colour white; sometimes tinged yellow or red.

**Variety 2. Indurated lithomarga.**

Hardness 4 to 7. The softer sorts adhere very strongly to the tongue when newly broken; the harder very moderately. Colours grey, yellow, red, brown, blue.

A specimen of lithomarga from Oftmund, analysed by Bergman, contained

- 60.0 silica, - 11.0 alumina, - 5.7 carbonat of lime, - 4.7 oxyd of iron, - 0.5 carbonat of magnesia, - 18.0 water and air.

**Species 4. Bole.**

Texture earthy. Fracture conchoidal. Lustre o. Transparency scarce 1. Hardness 4. Sp. gr. from 1.4 to 2. Acquires a polish by friction. Scarcely adheres to the tongue. Feels greasy. Colour yellow or brown; sometimes red; sometimes spotted.

The leumina earth which belongs to this species, according to the analysis of Bergman, contains

- 47.0 silica, - 19.0 alumina, - 6.0 carbonat of magnesia, - 5.4 carbonat of lime, - 5.4 oxyd of iron, - 17.0 water and air.

**Species 5. Fullers earth.**

Texture earthy. Structure sometimes flaky. Fracture imperfectly conchoidal. Lustre o. Opaque. Hardness 4. Receives a polish from friction. Does not adhere to the tongue. Feels greasy. Colour usually light green.

A specimen from Hampshire, analysed by Bergman, contained

- 51.8 silica, - 25.0 alumina, - 3.3 carbonat of lime, - 3.7 oxyd of iron, - 0.7 carbonat of magnesia, - 15.5 moisture.

100.0 This earth is used by fullers to take the grease out of their cloth before they apply soap. It is essential to fullers earth that the particles of silica be very fine; otherwise they would cut the cloth. Any clay, possessed of this last property, may be considered as fuller's earth; for it is the alumina alone which acts upon the cloth, on account of its strong affinity for greasy substances.

**Genus II. Colorific Earths.**

The minerals belonging to this genus consist of clay, mixed with so large a quantity of some colouring ingredient as to render them useful as paints. The colouring matter is commonly oxyd of iron, and sometimes charcoal.

**Species 1. Red chalk.**

*Redelle.*

Texture earthy. Fracture conchoidal. Lustre o. Opaque. Hardness 4. Sp. gr. inconsiderable. Colour dark red.

Feels rough. Stains the fingers. Adheres to the tongue. Falls to powder in water. Does not become ductile. When heated it becomes black, and at 149° Wedgwood melts into a greenish yellow frothy enamel.

Composed of clay and oxyd of iron.

**Species 2. Yellow chalk.**

*Redelle.*

Texture earthy. Fracture conchoidal. Hardness 3. Sp. gr. inconsiderable. Colour ochre yellow.

Feels smooth or greasy. Stains the fingers. Adheres to the tongue. Falls to pieces in water. When heated becomes red; and at 156° Wedgwood melts into a brown porous porcelain.

According to Sage, it contains

- 50 alumina, - 40 oxyd of iron, - 10 water, with some sulphuric acid.

**Species 3. Black chalk.**

Structure flat. Texture earthy. Fragments splintery. Lustre o. Opaque. Hardness 5. Sp. gr. 2.144 to 2.277. Colour black. Streak black.

Feels smooth. Adheres slightly to the tongue. Does not moulder in water. When heated to redness it becomes reddish grey.

According to Wiegleb, it is composed of

- 64.50 silica, - 11.25 alumina, - 11.00 charcoal, - 2.75 oxyd of iron, - 7.50 water.

97.00

**Species 4. Green earth.**

Texture earthy. Lustre o. Opaque. Hardness 6 to 7. Sp. gr. 2.637. Colour green.

Commonly feels smooth. Does not stain the fingers. Often falls to powder in water. When heated it becomes reddish brown; and at 147° Wedgwood melts into a black compact glaze.

Composed of clay, oxyds of iron and nickel.

**Genus III. Marl.**

A mixture of carbonat of lime and clay, in which the carbonat considerably exceeds the other ingredient, is Aggregates called marl.

Its texture is earthy. Lustre o. Opaque. Hardness from 4 to 8; sometimes in powder. Sp. gr. from 1.6 to 2.877. Colour usually grey, often tinged with other colours. Effervesces with acids.

Some marls crumble into powder when exposed to the air; others retain their hardness for many years.

Marls may be divided into two species: 1. Those which contain more silica than alumina; 2. Those which contain more alumina than silica. Mr Kirwan has called the first of these *siliceous*, the second *argillaceous* marls. Attention should be paid to this distinction when marls are used as a manure.

**Genus IV. Mould.**

By mould is meant the soil on which vegetables grow. It contains the following ingredients: silica, alumina, lime, magnesia (sometimes), iron, carbon derived from decayed vegetable and animal substances, carbonic acid, and water. And the good or bad qualities of soils depends upon a proper mixture of these ingredients. The silica is seldom in the state of an impalpable powder, but in grains of a greater or smaller size: Its chief use seems to be to keep the soil open and pervious to moisture. If we pass over the carbon, the iron, and the carbonic acid, the goodness of a soil depends upon its being able to retain the quantity of moisture which is proper for the nourishment of vegetables, and no more. Now the retentive power of a soil increases with the proportion of its alumina, lime, or magnesia, and diminishes as the proportion of its silica increases. Hence it follows, that in a dry country, a fertile soil should contain less silica, and more of the other earths, than in a wet country.

Giobert found a fertile soil near Turin, where it rains annually 30 inches, to contain

From 77 to 79 silica, 9 — 14 alumina, 5 — 12 lime.

Near Paris, where it rains about 20 inches annually, Mr Tillet found a fertile soil to contain

Coarse sand 25 Fine sand 21

- 46.0 silica, - 16.5 alumina, - 37.5 lime.

100.0

The varieties of mould are too numerous to admit an accurate description: we shall content ourselves, therefore, with mentioning the most remarkable.

**Species 1. Sand.**

This consists of small grains of siliceous stones not cohering together, nor softened by water. When the grains are of a large size, the soil is called gravel.

**Species 2. Clay.**

This consists of common clay mixed with decayed vegetable and animal substances.

**Species 3. Loam.**

Any soil which does not cohere so strongly as clay, but more strongly than chalk, is called loam. There are many varieties of it. The following are the most common. Earth and Variety 1. Clayey loam; called also strong, stiff, cold, and heavy, loam.

It consists of a mixture of clay and coarse sand.

Variety 2. Chalky loam.

A mixture of clay, chalk, and coarse sand; the chalk predominating.

Variety 3. Sandy loam.

A mixture of the same ingredients; the sand amounting to .8 or .9 of the whole.

Species 4. Till.

Till is a mixture of clay and oxyd of iron. It is of a red colour, very hard and heavy.

Sect. II. Aggregates of amorphous stones.

The aggregates which belong to this section consist of amorphous fragments of stones cemented together. They may be reduced to the following genera:

1. Sandstone, 2. Puddingstone, 3. Amygdaloid, 4. Breccia.

Genus I. Sandstone.

Small grains of sand, consisting of quartz, flint, hornblende, siliceous flintus, or felspar, and sometimes of mica, cemented together, are denominated sandstones. They feel rough and sandy; and when not very hard, easily crumble into sand. The cement or basis by which the grains of sand are united to each other is of four kinds; namely, lime, alumina, silica, iron. Sandstones, therefore, may be divided into four species.

Species 1. Calcareous sandstones.

Calcareous sandstones are merely carbonat of lime or marl, with a quantity of sand interposed between its particles. Though the quantity of sand, in many cases, far exceeds the lime, calcareous sandstones are sometimes found crystallized; and, in some cases, the crystals, as might be expected, have some of the forms which distinguish carbonat of lime. Thus the calcareous sandstone of Fountainbleau is crystallized in rhomboidal tables. It contains, according to the analysis of Laffon:

- 62.5 siliceous sand, - 37.5 carbonat of lime.

Calcereous sandstones have commonly an earthy texture. Their surface is rough. Their hardness from 6 to 7. Their specific gravity about 2.5 or 2.6. Their colour grey; sometimes yellowish or brown. They are sometimes burned for lime.

Species 2. Aluminous sandstones.

The basis of argillaceous sandstones is alumina, or rather clay. Their structure is often flat. Their texture is compact, and either fine or coarse grained, according to the size of the sand of which they are chiefly composed. Their hardness is from 6 to 8, or even 9. Their colour is usually grey, yellow, or brown.

They are often formed into mill-stones, filtering-stones, and coarse whet stones.

Species 3. Siliceous sandstones.

Siliceous sandstones consist of grains of sand cemented together by silica, or some substance which consists chiefly of silica or flint. They are much harder than any of the other species.

Sometimes stones occur, consisting of grains of lime cemented together with silica. These stones are also denominated siliceous sandstones.

Species 4. Ferruginous sandstones.

The iron which acts as a cement in ferruginous sandstones is not far from a metallic state. When iron is completely oxidated, it loses the property of acting as a cement. This is the reason that ferruginous sandstones, when exposed to the air, almost always crumble into powder.

The colour of ferruginous sandstones is usually dark red, yellow, or brown. The grains of sand which compose them are often pretty large. Their hardness is commonly inconsiderable.

Genus II. Pudding Stone.

Pebbles of quartz, flint, or other similar stones of a dingy round or elliptical form, from the size of rape seed to that of an egg, cemented together by a siliceous cement, often mixed with iron, have been denominated pudding stones.

Pudding stones, of course, are not inferior in hardness to quartz, flint, chalcedony, &c., of which the pebbles may consist. The colour of the cement is usually yellow, brown, or red. Its fracture is conchoidal.

The finer sorts of pudding stones are capable of a fine polish; the coarser are used for mill-stones.

Genus III. Amygdaloid.

Rounded or elliptical masses of chalcedony, zeolite, limestone, lithomarga, fleatites, green earth, garnets, hornblende, or opal, cemented together by a basis of indurated clay, trap, mullen, wakken or kragg, constitute an amygdaloid.

Amygdaloids are opaque. They have no lustre. Their fracture is uneven or conchoidal. Hardness 6 to 9. Their colours are as various as the ingredients of which they are composed.

Genus IV. Breccia.

Angular fragments of the same species of stone agglutinated together, constitute a breccia. Thus calcareous breccia consists of fragments of marble cemented together by means of lime.

Sect. III. Aggregates of Crystals.

The minerals belonging to this section consist either of crystals of different kinds cemented together, or of crystals and amorphous stones cemented together.

They may be reduced under the following genera:

1. Granite, 2. Sienite, 3. Granatine, 4. Granitell, 5. Granilit, 6. Trap, 7. Porphyry.

Genus I. Granite.

An aggregate of felspath, quartz, and mica, whatever be the size or the figure of the ingredients, is denominated granite. This aggregate may be divided into two species, namely, common granite, and syenite granite or gnais.

Species 1. Common granite.

Its structure is always granular. The felspar is often Common granites differ much in their appearance, according to the size, proportion, colour, and figure of their component parts. They are commonly very hard; their specific gravity varies from 2.5388 to 2.9564.

**Species I.** Shiftofe granite or gneiss.

The structure of gneiss is always flaty, and this constitutes its specific character. In gneiss, the proportion of quartz and felspar is nearly equal; the proportion of mica is smallest. It is evidently subject to the same varieties with common granite.

**Genus II.** Sienite.

Mr Werner has given the name of sienite to aggregates composed of felspar, hornblende, and quartz; or of felspar, hornblende, quartz, and mica. These aggregates were formerly confounded with quartz.

Sienite is found both of a granular and flaty structure; it might, therefore, like granite, be divided into two species. In sienite the quartz is commonly in by far the smallest proportion.

**Genus III.** Granatine.

Mr Kirwan has applied the name granatine to the following aggregates:

| Quartz, Felspar, Short. | Quartz, Mica, Garnet. | Quartz, Hornblende, Jade. | Felspar, Mica, Short. | |-------------------------|-----------------------|--------------------------|----------------------| | Quartz, Felspar, Jade. | Quartz, Short, Hornblende, Garnet. | Quartz, Jade, Garnet. | Felspar, Quartz, Serpentine. | | Quartz, Mica, Short. | Quartz, Short, Garnet. | Quartz, Hornblende, Hornblende, Steatites. | Felspar, Quartz, Steatites. | | Quartz, Mica, Jade. | | | |

One of these aggregates, namely, quartz, mica, garnet, was called by Cronstedt norka or marksten.

**Genus IV.** Granitell.

Mr Kirwan gives the name of granitell to all aggregates composed of any two of the following ingredients: quartz, felspath, mica, florl, hornblende, jade, garnet, steatites. The most remarkable of these are:

| Quartz, Felspar, Hornblende, Steatites. | Quartz, Felspar, Mica, Jade. | Felspar, Hornblende, Short. | |----------------------------------------|-------------------------------|-----------------------------| | Quartz, Mica, Jade. | | | | Quartz, Short, Garnet. | | |

Some of these aggregates have received particular names. The aggregate of quartz and mica, when its structure is flaty, is called by Werner shiftofe mica; by the Swedes, it is denominated skifsten, whatever be its structure.

The aggregate of hornblende and mica is called grunstein, from the dark green colour which it usually has.

**Genus V.** Granilitre.

Under the name of granilitre, Mr Kirwan comprehends all aggregates containing more than three ingredients. Of these the following are the most remarkable:

| Quartz, Felspar, Mica, Short. | Quartz, Sulph. of barytes, Mica, Short. | |-------------------------------|----------------------------------------| | Quartz, Felspar, Mica, Garnet. | Quartz, Sulph. of barytes, Mica, Hornblende. |

**Genus VI.** Trap (P).

Under this genus we clas not only what has commonly been called trap, but also wacken, and mullen, and kragstone of Kirwan.

**Species I.** Common trap.

This stone is very common in Scotland, and is known by the name of whinstone. Whole hills are formed of it; and it occurs very frequently in large rounded detached fragments. Sometimes it assumes the form of immense columns, and is then called basalt. The Giants Causeway in Ireland, the island of Staffa, and the south side of Arthur's Seat in Scotland, are well known instances of this figure.

Its texture is earthy or compact. Its fracture uneven. Its lustre commonly o. Opaque. Hardness 8 to 9. Not brittle. Sp.gr. from 2.78 to 3.021. Colour black, with a tinge of grey, blue, or purple; sometimes blackish or reddish brown; in some cases greenish grey. By exposure to the atmosphere, it often becomes invested with a brownish rind. Before the blow pipe, it melts per se into a more or less black glass.

Trap consists of small crystals of hornblende, felspar, olivine, &c., usually set in a ground-composed apparently of clay and oxyd of iron. A specimen, in the form of basaltic, from Staffa, analysed by Dr Kennedy of Edinburgh, contained 48 silica, 16 alumina, 16 oxyd of iron, 9 lime, 5 moisture, 4 soda, 1 muriatic acid.

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(1) Kirw. I. 231 and 431.—Fayard de St Fond. Essai sur P.Hift. Nat. des Roche de Trap.—Phil. Trans. passim.

See also a very ingenious set of experiments on the fusion of trap, by Sir James Hall in Trans. Edin. V. 43. A specimen from Salisbury rock, near Edinburgh, contained, according to the analysis of the same gentleman,

- 46.0 silica, - 19.0 alumina, - 17.0 oxyd of iron, - 8.0 lime, - 4.0 moisture, - 3.5 soda, - 1.0 muriatic acid.

Dr Kennedy conducted these analyses with great ingenuity and judgment; and the discovery in which they terminated, that trap contains soda, is certainly of importance, and may lead to valuable consequences both in a geological and mineralogical view.

**Species 2. Wacken.**

This stone often forms considerable parts of hills, and, like trap, is amorphous. Its texture is earthy. Its fracture usually even. Lustre O. Opaque. Hardness 6 to 9. Sp. gr. from 2.535 to 2.893. Colour grey, with a shade of green, black, red, brown. When exposed to the atmosphere, it withers and becomes more grey.

It melts into a grey porous flax.

**Species 3. Mullen.**

This stone is also found in considerable masses, and sometimes has a tendency to a columnar form like basalt. Texture earthy. Fracture uneven, and fine splintery. Lustre O, except from some shining particles of basaltine. Opaque. Hardness from 7 to 9. Sp. gr. from 2.6 to 2.738. Colour ash or bluish grey; sometimes mixed with ochre yellow, in consequence of the decomposition of the stone. At 130° Wedgwood it melts into a black compact glass.

When mullen is exposed to the air, its surface becomes covered with a greyish white rind, sometimes slightly ochre.

**Species 4. Kragstone.**

This stone, which, like the others, forms considerable parts of rocks, was formed into a distinct species by Mr Kirwan. Its texture is earthy. It is exceedingly porous, and the pores are often filled with the crystals of other minerals. Fracture uneven. Lustre O. Opaque. Hardness 5 to 7. Sp. gr. 2.314. Feels rough and harsh. Colour reddish grey. Streak yellowish grey. At 130° Wedgwood it melts into a reddish brown porcelain mass.

**Genus VII. Porphyry.**

Any stone which contains scattered crystals or grains of felspar, visible to the naked eye, is denominated a porphyry. Besides felspar, porphyries generally contain small crystals of quartz, hornblende, and mica. These crystals are usually of a different colour from the stone in which they are found, and they are stuck in it as in a cement. It is evident from this definition, that the number of porphyries must be great. Each species receives its name from the stone which forms its basis. To describe them would be unnecessary. We shall only give a catalogue of the principal species.

1. Hornstone porphyry. 2. Pitchstone porphyry. 3. Hornblende porphyry. 4. Felspar or petunite porphyry. 5. Clay porphyry. 6. Hornblende porphyry. 7. Trap porphyry. 8. Wacken porphyry. 9. Mullen porphyry. 10. Krag porphyry. 11. Argillaceous porphyry. 12. Pottstone porphyry. 13. Serpentine porphyry. 14. Sandstone porphyry.

The aggregates belonging to this section compose most of the mountains of the globe. In giving an account of them, we have adhered implicitly to the arrangement most generally received by mineralogists. It must be acknowledged, that this arrangement is by no means complete, and that some of the genera are too vague to be of much use. The number of aggregates already discovered is too great for giving to each a particular name. Perhaps it would be better henceforth to adopt the method proposed by Mr Hauy, namely, to constitute the genera from that ingredient which enters most abundantly into the aggregate, and which forms as it were its basis, and to distinguish the species according to the nature and proportion of the other ingredients. According to this plan, the aggregates hitherto discovered have been divided by Hauy into the following genera:

1. Felspathic rock. 2. Quartzose rock. 3. Micaceous rock. 4. Chloritic rock. 5. Serpentine rock. 6. Trappean rock. 7. Hornblendean rock. 8. Petro-siliceous rock. 9. Garnet rock. 10. Calcareous rock. 11. Argillaceous rock. 12. Corneous rock.

**Sect. IV. Volcanic Aggregates.**

Aggregates formed by volcanoes may be reduced to the following genera.

1. Lava. 2. Tufa. 3. Pumice. 4. Ashes.

**Genus I. Lava.**

All substances which have issued out of a volcano in a state of fusion are called lavas. They have been divided into three species.

**Species 1. Vitreous lava.**

Found in small pieces. Texture glossy. Fracture conchoidal. Lustre 3. Transparency from 3 to 1. Hardness 9 to 10. Sp. gr. from 2 to 3. Colour blackish, greenish, or whitish. Commonly somewhat porous.

**Species 2. Cellular lava.**

This species is full of cells. Surface rough and full of cavities. Texture earthy. Lustre O. Opaque. Hardness 7 to 9. Sp. gr. varies, but does not exceed 2.8. Colour brown or greyish black. Commonly somewhat magnetic.

**Species 3. Compact lava.**

This species is the most common of all; it runs into the the second by insensible degrees; and indeed is seldom found of any considerable size without some pores. It bears in general a very strong resemblance to trap.

A specimen of the lava of Catania in Sicily, analysed by Dr Kennedy, contained:

- 51.0 silica, - 19.0 alumina, - 14.5 oxyd of iron, - 9.5 lime, - 4.0 soda, - 1.0 muriatic acid.

Thus we see, that the resemblance between trap and lava holds not only in their external appearance, but also in their component parts.

**Class II.**

**Genus I. Potas.**

Sp. 1. Sulphat of potas. 2. Nitrat of potas.

**Class III. Combustibles.**

The combustible substances belonging to the mineral kingdom, excluding the metals, may be comprehended under the following genera:

1. Sulphur. 2. Carbon. 3. Bitumen. 4. Coal. 5. Amber.

**Genus I. Sulphur.**

Species 1. Native sulphur.

This substance is found abundantly in many parts of the world, especially near volcanoes, as Hecla, Aetna, Vesuvius, the Lipari islands, &c. It is either in the state of powder, or massive, or crystallized. The primitive form of its crystals is an octahedron, composed of two four-sided pyramids, joined base to base. Sometimes they are truncated near their bases, and a low four-sided pyramid rises from the truncature; this pyramid is also sometimes truncated near its apex. Finally, one of the edges of the pyramids is sometimes truncated. For figures of these varieties, and for the laws of their formation, we refer to Mr Lefroy.

Colour yellow, with a shade of green; sometimes reddish (q.). Lustre greasy, 2. Transparency varies from 0 to 4. Causes double refraction. Texture compact. Hardness 4 to 5. Brittle.—For its other properties, we refer to Chemistry in this Suppl.

Sometimes sulphur is mixed with different proportions of earths. These combinations are hardly susceptible of accurate description.

Sulphur combines also with metals. These combinations shall be described in the fourth class.

**Genus II. Carbon.**

This genus comprehends all minerals composed of pure carbon, or of carbon combined with a little earth.

Species 1. Diamond.

This mineral, which was well known to the ancients,

Species 1. Naphtha.

This substance is found sometimes on the surface of the water of springs, and sometimes issuing from certain strata. It is found in great abundance in Persia.

It is as fluid and transparent as water. Colour white or yellowish white. Smell strong, but not disagreeable. Sp. gr. when white, .728 or .729; when yellowish, .84-75. Feels greasy. Catches fire on the approach of flame, burns with a white flame, and leaves scarce any residuum.

Insoluble in alcohol. Does not freeze at 0° Fahrenheit. When pure naphtha is exposed to the air, it becomes yellow and then brown; its consistence is increased, and it passes into petroleum.

Species 2. Petroleum.

This substance is also found in Persia, and likewise in many countries in Europe, particularly Italy, France, Switzerland, Germany, Sweden, England, and Scotland.

Not so fluid nor transparent as water. Colour yellow, either pale or with a shade of red or green; reddish brown and reddish black. Smell that of naphtha, but less pleasant. Sp. gr. 87-83. When burned it yields a foot, and leaves a small quantity of coally residuum.

By exposure to the air it becomes like tar, and is then called mineral tar.

Species 3. Mineral tar.

This substance is found in many parts of Asia, America, and Europe. It is viscid, and of a black, brownish black, or reddish colour. Smell sometimes strong, but often faint. Sp. gr. 1.1. When burned, emits a disagreeable bituminous smell. By exposure to the air it passes into mineral pitch and maltha.

Species 4. Mineral pitch and maltha.

This substance has a strong resemblance to common pitch. When the weather is warm it is soft, and has some tenacity; it is then called adhesive mineral pitch; when the weather is cold, it is brittle; its hardness is 5; and its fracture has a glairy lustre. In this state it is called maltha. Colour black, dark brown, or reddish. Lustrous. Opaque. Sp. gr. from 1.45 to 1.67. Does not stain the fingers. On a white hot iron it flames with a strong smell, and leaves a quantity of grey ashes. It is the presence of the earths which compose these ashes that the great specific gravity of this bitumen is to be ascribed. By farther induration, it passes into asphalt.

Species 5. Asphalt.

This substance is found abundantly in many parts of Europe, Asia, and America, especially in the island of Trinidad.

Colour black or brownish black. Lustrous, greasy. Opaque. Fracture conchoidal, of a glairy lustre. Hardness from 7 to 8. Very brittle. Sp. gr. 1.07 to 1.65. Feel smooth, but not greasy. Does not stain the fingers. Has little or no smell, unless when rubbed or heated. When heated melts, swells, and inflames; and when pure, burns without leaving any ashes.

Species 6. Elastic bitumen.

This substance was found about the year 1786 in the lead

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(1) This name was given by Hauy from σικός, a coal. **MINERALOGY**

A specimen of the flaty kind from Ayrshire, called *splint coal*, was composed of:

- 47.62 charcoal, - 32.52 maltha, - 20.02 earths.

100.14

Cannel coal is susceptible of polish, and, like jet, is often wrought into trinkets.

**SPECIES 3. Common coal.**

This very useful combustible is never found in the primitive mountains, but only in the secondary mountains, or in plains formed of the same materials with them. It is always in strata, and generally alternates with clay, sandstone, or limestone.

Colour black, more or less perfect. Lustre usually greasy or metallic, 2 to 4. Opaque. Structure generally flaty. Texture often foliated. Fracture various. Hardness 4 to 6. Sp. gr. 1.25 to 1.37. Usually itans the fingers. Takes fire more slowly, and burns longer, than the last species. Cakes more or less during combustion.

Of this species there are many varieties, distinguished in Britain by the names of coking coal, rock coal, &c. These are too well known to require any description.

Mr Kirwan analysed a variety of different kinds of coal: The result of his experiments may be seen by the following table:

| Whitchurch coal | Wigan | Swansea | Leekin | |-----------------|-------|---------|-------| | 57.0 | 61.73 | 73.53 | 74.43 | | 41.3 | 30.7 | 23.14 | 23.37 | | 1.7 | 3.33 | 5.42 | |

charcoal, maltha & earths

**SPECIES 4. Spurious coal.**

This mineral is generally found amidst strata of genuine coal. It is also called *parrot coal* in Scotland.

Colour greyish black. Lustre 0 to 1. Structure usually flaty. Texture earthy. Hardness 7 to 8. Sp. gr. 1.5 to 1.6 Generally explodes, and bursts when heated.

Composed of charcoal, maltha, and asphalt, and above 10% of flaky matter.

**GENUS V. AMBER.**

**SPECIES 1. Common amber.**

This substance, called *elektron* by the ancients, is found in different countries; but most abundantly in Prussia, either on the sea shore, or under ground at the depth of about 100 feet, repelling on wood coal. It is in lumps of different sizes.

Colour yellow. Lustre 3 to 2. Transparency 2 to 4. Fracture conchoidal. Hardness 5 to 6. Sp. gr. 1.078 to 1.085. Becomes electric by friction.

If a piece of amber be fixed upon the point of a knife, and then kindled, it burns to the end without melting.

By distillation it yields succinic acid.

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(1) It was called *gogathos* by the ancients, from the river Ganges in Licia, near which it was found; *jayet* in French, *guayacan* in Spanish, *gagath* in German.

(2) Hence it has been called *cannel coal*. *Candle*, in the Lancashire and Scotch dialect, is pronounced *cannel*. Class IV. Metallic Ores.

This class comprehends all the mineral bodies composed either entirely of metals, or of which metals constitute the most considerable and important part. It is from the minerals belonging to this class that all metals are extracted; for this reason they have obtained the name of ores.

The metals hitherto discovered amount to 21; we shall therefore divide this class into 21 orders, allotting a distinct order for the ores of every particular metal.

Metals exist in ores in one or other of the four following states. 1. In a metallic state, and either solitary or combined with each other. 2. Combined with sulphur. 3. In the state of oxyds. 4. Combined with acids. Each order therefore may be divided into the four following genera.

1. Alloys. 2. Sulphurets. 3. Oxyds. 4. Salts.

It must be observed, however, that every metal has not hitherto been found in all these four states, and that some of them are hardly susceptible of them all. Some of the orders therefore want one or more genera, as may be seen from the following table.

| Order I. Gold ores. | Order X. Antimonial ores. | |---------------------|---------------------------| | 1. Alloys. | 1. Alloys. | | | 2. Sulphurets. | | Order II. Silver ores. | Order XI. Bismuth ores. | | 1. Alloys. | 1. Alloys. | | 2. Sulphurets. | 2. Sulphurets. | | 3. Oxyds. | 3. Oxyds. | | 4. Salts. | |

| Order III. Platinum ores. | Order XII. Arsenic ores. | |---------------------------|--------------------------| | 1. Alloys. | 1. Alloys. | | | 2. Sulphurets. | | | 3. Oxyds. | | | |

| Order IV. Ores of mercury. | Order XIII. Cobalt ores. | |----------------------------|--------------------------| | 1. Alloys. | 1. Alloys. | | 2. Sulphurets. | 2. Sulphurets. | | 3. Oxyds. | 3. Oxyds. | | 4. Salts. | |

| Order V. Copper ores. | Order XIV. Nickel ores. | |----------------------------|--------------------------| | 1. Alloys. | 1. Sulphurets. | | 2. Sulphurets. | 2. Oxyds. | | 3. Oxyds. | 3. Salts. | | 4. Salts. | |

| Order VI. Iron ores. | Order XV. Manganese ores. | |----------------------------|--------------------------| | 1. Alloys. | 1. Oxyds. | | 2. Sulphurets. | 2. Salts. | | 3. Carburets. | | | 4. Silicated iron. | | | 5. Oxyds. | | | 6. Salts. | |

| Order VII. Tin ores. | Order XVI. Tungsten ores. | |----------------------------|--------------------------| | 1. Sulphurets. | 1. Oxyds. | | 2. Oxyds. | 2. Salts. | | | |

| Order VIII. Lead ores. | Order XVII. Ores of molybdenum. | |----------------------------|---------------------------------| | 1. Sulphurets. | 1. Sulphurets. | | 2. Oxyds. | 2. Salts. | | 3. Salts. | |

| Order IX. Zinc ores. | Order XVIII. Ores of uranium. | |----------------------------|--------------------------------| | 1. Sulphurets. | 1. Oxyds. | | 2. Oxyds. | 2. Salts. | | 3. Salts. | |

| Order XXI. Ores of chromium. | Order XIX. Ores of titanium. | |------------------------------|------------------------------| | 1. Oxyds. | 1. Oxyds. | | | 2. Salts. | | | |

Order I. GOLD ORES.

No metal perhaps, if we except iron, is more widely scattered through the mineral kingdom than gold. Hitherto it has been found only in a metallic state; most commonly in grains, ramifications, leaves, or rhombohedral, octahedral, or pyramidal crystals. It is generally mixed with quartz, though there are instances of its having occurred in calcareous rocks. It is not uncommon also to find it disseminated through the ores of other metals; especially iron, mercury, copper, and zinc. The greatest quantity of gold is found in the warmer regions of the earth. It abounds in the sands of many African rivers, and is very common in South America and India. Europe, however, is not destitute of this metal. Spain was famous in ancient times for its gold mines, and several of the rivers in France contain it in their sands. But the principal gold mines in Europe are those of Hungary, and next to them those of Salzburg. Gold also has been discovered in Sweden and Norway, and more lately in the county of Wicklow in Ireland.

Genus I. Alloys of gold.

Species 1. Native gold.

Native gold is never completely pure; it is alloyed with some silver or copper, and sometimes with iron. In the native gold found in Ireland, indeed, the quantity of alloy appears to have been exceedingly small.

Its colour is yellow. Lustrous metallic. Fracture hackly. Hardness 5. Sp. gr. from 12 to 19.

Order II. SILVER ORES.

Silver is found most commonly in quartz, limestone, where hornblende; or combined with the ores of other metals, found most commonly with copper, antimony, zinc, cobalt, and lead. This last metal indeed is seldom totally deficient of silver.

Genus I. Alloys of silver.

Species 1. Native silver.

Native silver, so called because the silver is nearly in a state of purity, forms the principal part of some of the richest silver mines in the world. It is sometimes found in small lumps; sometimes crystallized in cubes, hexagonal prisms, octahedrons, or dodecahedrons; sometimes in leaves, or threads, often connected with each other as to resemble branches of trees, and therefore called dendrites. The silver in the famous mines of Potosi has this last form. When newly extracted, it is not unlike small branches of fir.

The colour of native silver is white; often tarnished. Lustrous metallic. Fracture hackly. Hardness 6. Meltable. Sp. gr. from 10 to 10.338.

The silver in this species is almost constantly alloyed with from .03 to .05 of some other metal, frequently gold or arsenic. SPECIES 2. Alloy of silver and gold.

Auriferous native silver.

This alloy is not uncommon in silver mines. Its colour is yellowish white. Its lustre metallic. Hardness 5. Malleable. Sp. gr. above 10.6. Dr Fordyce found a specimen from Norway composed of

\[ \begin{align*} 72 & \text{ silver}, \\ 28 & \text{ gold}. \end{align*} \]

100

SPECIES 3. Alloy of silver and antimony.

Antimoniated silver ore.

This alloy, which is found in the silver mines of Spain and Germany, is sometimes in grains or lumps, and sometimes crystallized in six-sided prisms, whose sides are longitudinally channelled.

Its colour is white. Its lustre metallic. Hardness 10. Brittle. Sp. gr. from 9.44 to 9.69. Texture foliated. Fracture conchoidal. Before the blow-pipe the antimony evaporates in a grey smoke, and leaves a brownish fume, which tinges borax green. If borax be used at first, a silver bead may be obtained.

This alloy was long supposed to contain arsenic. Bergman examined it, and found only silver and antimony. His analysis has been confirmed by the experiments of Vauquelin and Selb. According to Selb, it is composed of 89 silver, 11 antimony.

100

A specimen, analysed by Klaproth, contained

84 silver, 16 antimony.

100

Another specimen contained

76 silver, 24 antimony.

100

GENUS II. SULPHURETS OF SILVER.

SPECIES 1. Common sulphuret of silver.

Vitreous silver ore.

This ore occurs in the silver mines of Germany and Hungary. It is sometimes in masses, sometimes in threads, and sometimes crystallized. Its crystals are either cubes or regular octahedrons, whose angles and edges are often variously truncated. For a description of the varieties produced by these truncatures, we refer the reader to Romé de Lisle.

Its colour is dark bluish grey, inclining to black; often tarnished. Internal lustre metallic. Texture foliated. Fracture uneven. Hardness 4 to 5. May be cut with a knife like lead. Flexible and malleable. Sp. gr. 6.099 to 7.215. In a gentle heat the sulphur evaporates. Melts when heated to redness.

A specimen of this ore, analysed by Klaproth, contained

85 silver, 15 sulphur.

100

SPECIES 2. Antimoniated silver ore.

Sulphuret of silver with antimony and iron.

This ore, which occurs in Saxony and Hungary, seems to be sulphuret of silver contaminated with antimony and iron, and ought therefore, in all probability, to be considered merely as a variety of the last species.

It is sometimes in masses, but more frequently crystallized in six-sided prisms, tables, or rhomboids; generally indistinct and accumulated together.

Its colour is iron grey; often tarnished. Its lustre metallic. Fracture uneven. Hardness 4 to 5. Brittle. Sp. gr. 7.208. Before the blow-pipe the sulphur and antimony exhale, leaving a bead, which may be freed from iron by fusion with nitre and borax.

A specimen of this ore, analysed by Klaproth, contained

66.5 silver, 12.0 sulphur, 10.0 antimony, 5.0 iron, 1.0 silica, 0.5 arsenic and copper.

95.0

SPECIES 3. Sulphuret of silver and copper.

Cupriferous sulphuret of silver ore.

This ore, which is found in the Korbolokinsk mountain of silver mines in Siberia, was first described by Mr Renovantz, and copper. It is an amorphous mass, varying in size from that of Kirwan, the thumb to that of the fist.

Its colour is bluish grey like lead. Lustre metallic. Hardness 5 to 6. Brittle. Its powder, when rubbed on the skin, gives it a black colour and a leaden glint. Before the blow-pipe the sulphuret of silver melts readily; that of copper with difficulty. This ore is composed of about

42 silver, 21 copper, 35 sulphur.

98

GENUS III. OXYDS OF SILVER.

SPECIES 1. Calciform silver ore.

Calciform silver ore.

This ore was first described by Mr Widenman. It is sometimes in masses, sometimes disseminated through other minerals.

Its colour is greyish black. Its streak bright. Its lustre metallic. Its fracture uneven. Hardness 4 to 5. Brittle. Sp. gr. considerable. Effervesces with acids. Melts easily before the blow-pipe. Froths with borax.

According to Selb, it contains 72.5 silver, 15.5 copper, 12.0 carbonic acid.

100.0

SPECIES 2. Red silver ore.

Red silver ore.

This ore is very common in several German silver mines. It occurs in masses, disseminated and crystallized. The primitive form of its crystals is a dodecahedron, whose sides are equal rhombs, and which may be... considered as a six-sided rhombooidal prism, terminated by three-sided summits. Sometimes the prism is lengthened, and sometimes its edges, or those of the terminating summits, or both, are wanting. For a description and figure of these varieties, we refer to De Lisle† and Haüy‡.

Its colour is commonly red. Streak red. External lustre metallic; internal common. Transparency from 3 to 1; sometimes opaque. Fracture flat conchochoid. Hardness 5 to 7. Brittle. Sp. gr. from 5.44§ to 5.592¶. Becomes electric by friction, but only when insulated. Soluble in nitric acid without effervescence*. Before the blow pipe melts, blackens, burns with a blue flame, gives out a white smoke with a slight garlic smell, and leaves a silver bead†.

Variety 1. Light red.

Colour intermediate between blood and cochineal red; sometimes variegated. Streak orange red. Powder black.

Variety 2. Dark red.

Colour commonly between dark cochineal red and lead grey; sometimes nearly black and without any shade of red. Streak dark crimson red.

This ore was long supposed to contain arsenic. Klaproth first ascertained its real composition‡; and his analysis has been confirmed by Vanquelin, who found a specimen composed of 67.75% silver, 6.00% iron, 21.00% muriatic acid, 1.25% sulphuric acid, 1.75% alumina.

The alumina can only be considered as mixed with the ore. Sometimes its quantity amounts to .67 of the whole.

ORDER III. ORES OF PLATINUM (v).

Hitherto no mine of platinum has been discovered. Mines. It is found in small scales or grains on the sands of the river Pintos, and near Carthagena in South America. It is always in a metallic state, and always combined with iron.

GENUS I. ALLOYS OF PLATINUM.

SPECIES I. Native platinum.

Its colour is whitish iron grey. Magnetic. Sp. gr. from 12 to 16. Soluble in nitro-muriatic and oxy-muriatic acids.

ORDER IV. ORES OF MERCURY.

Mercury is employed in medicine; it serves to separate silver and gold from their ores; the silvering of looking glasses, gilding, &c., are performed by means of it; and its sulphuret forms a beautiful paint.

Mercury abounds in Europe, particularly in Spain, Germany, and Hungary; it is found also in China (z), the Philippines*, and in Peru, and perhaps Chili (a) in South America. The most productive mines of foreign mercury are those of Idria†; of Almaden, near Cordoba, in Spain, which were wrought by the Romans (b); of the Palatinate‡; and of Guanac Velica in Peru (c).

Mercury has never been found in Britain, nor has any mine worth working been discovered in France. It occurs most commonly in argillaceous shittus, limestones, and sandstones.

GENUS I. ALLOYS OF MERCURY.

SPECIES I. Native mercury.

Native mercury is found in most mercurial mines; it is in small globules, scattered through different kinds of stones, clays, and ores.

Fluid. Colour white. Sp. gr. about 13.6.

---

(x) Kirse, II. 113.—Lamanna, Nov. Comm. Petropol. XIX. 482.—Monnet, Mem. Soc. Etrang. IX. 717.

(y) See Brownrigg, Phil. Trans. XLVI. 534.—Lewis, ibid. XLVIII. 638, and L. 148.—Margraf, Mem. Berlin, 1757, p. 314.—Macquer, Mem. Par. 1758, p. 119.—Buffon, Jour. de Phys. III. 324.—Moreau, ibid. VI. 193.—Bergman, Opus. II. 166.—Tillet, Mem. Par. 1779, p. 373, and 385, and 545.—Crelle, Crelle's Annals, 1784, 1 Band. 328.—Willis, Manchester Memoirs, III. 407.—Muffin Pushkin, Ann. de Chim. XXIV. 205.—Moreau, ibid. XXV. 3.

(z) See Entrecelle's Lettres Edificantes.

(a) See Molina's Natural History of Chili.

(b) See Bowle's Natural History of Spain, and Jour. de Min. N° xxxi. p. 555.

(c) See Ulloa's Memoirs concerning America. This mineral has been found in the silver mine of Salzberg, in the province of Dalecarlia, in Sweden; in the mines of Deux Ponts, in the Palatinate; and in other places. It is in thin plates, or grains, or crystals, flattened in cubes, parallelepipeds, or pyramids.

Its colour is silvery white or grey. Lustrous metallic. Creaks when cut. Sp. gr. above 10. Tinges gold white. Before the blow-pipe the mercury evaporates and leaves the silver.

A specimen of this amalgam, analysed by Klaproth, contained:

- 64 mercury, - 36 silver.

Sometimes it contains a mixture of alumina, and sometimes the proportion of mercury is so great that the amalgam is nearly as soft as pate.

**Genus II. Sulphures of Mercury.**

**Species I. Common sulphuret.**

Native cinabar.

This ore, which is found in almost all mercurial mines, is sometimes in veins, sometimes disseminated, sometimes in grains, and sometimes crystallized. The form of its crystals is a tetrahedron or three-sided pyramid, most commonly wanting the summit; sometimes two of these pyramids are joined base to base; and sometimes there is a three-sided prism interposed between them.

Its colour is red. Its streak red and metallic. Lustre which crystallizes 2 to 3; when amorphous, often 0. Transparency, when crystallized, from 1 to 3; when amorphous, often 0. Texture generally foliated. Hardness from 3 to 8. Sp. gr. from 5.419 to 10.1285.

Before the blow-pipe evaporates with a blue flame and sulphurous smell. Insoluble in nitric acid.

Variety 1. Dark red.

Colour cochineal red. Hardness 6 to 7. Sp. gr. when pure, 10.1285; sometimes only 7.2, or even 6.158.

Variety 2. Bright red.

Colour commonly scarlet. Sp. gr. 6.9022 to 5.419.

**Genus III. Oxyds of Mercury.**

**Species I. Hepatic mercurial ore.**

This ore, which is the most common in the mines of Idria, is always amorphous, and is often mixed with native mercury and cinabar.

Its colour is somewhat red. Its streak dark red and brighter. Lustre commonly metallic. Hardness from 6 to 8. Sp. gr. from 9.2301 to 7.186. When heated the mercury evaporates.

Though this ore has never been accurately analysed, chemists have concluded that the mercury which it contains is in the state of a red oxyd, because it is insoluble in nitric and soluble in muriatic acid. When purchased, it contains about .57 of mercury. It contains also some sulphur and iron.

Werner has divided this species into two varieties, the compact and the flaky. The second is often nothing more than bituminous shale impregnated with oxyd of mercury.

**Genus IV. Mercurial Salts.**

**Species I. Muriat of mercury.**

Coronour mercury.

This ore, which occurs in the Palatinate, is sometimes in scales, sometimes in grains, and sometimes crystallized. Its crystals are either small four or fixed sided prisms whose sides are rhombic, or cubes, or four-sided pyramids wanting their angles. They are always very small and generally confused.

Its colours are various; but it is most frequently white. Its lustre, when white, is pearly. Sometimes opaque, and sometimes semitransparent. Evaporates before the blow-pipe.

Mr Woulfe discovered, that this ore generally contains some sulphuric acid. Specimens have been found in which the quantity of sulphuric acid exceeds that of the muriatic.

**Order V. Copper Ores.**

Many of the most useful utensils are formed of copper; it enters largely into the composition of brass, bronze, and bell metals; not to mention the dyes and paints of which it is the basis.

Copper mines abound in most countries. They are wrought in China, Japan, Sumatra; the north of Africa; in Chili and Mexico; and in most parts of Europe; especially Britain, Germany, Russia, Hungary.

Copper is found most commonly in rocks of hornblende, sluffus, and quartz.

**Genus I. Alloys of Copper.**

**Species I. Native copper.**

Native copper occurs now and then in the greater number of copper mines. Sometimes it is in masses, sometimes in plates and threads, which assume a variety of forms; and sometimes, as in Siberia, it is crystallized in cubes, or other forms nearly resembling cubes.

Colour commonly that of copper, but sometimes dark brown. Lustre metallic. Streak brighter. Fracture hackly. Flexible and malleable. Hardness 6 to 7. Sp. gr. from 7.6 to 8.544.

**Species 2. White copper ore.**

Alloy of copper, iron, and arsenic.

This ore, which is said to be uncommon, occurs in masses. Colour white. Lustre metallic. Fracture uneven. Hardness 8 to 9. Brittle. Sp. gr. considerable.

Before the blow-pipe gives out a white arsenical smoke, and melts into a greyish black slag.

**Genus II. Sulphures of Copper.**

**Species I. Common sulphuret of copper.**

Vitrous copper ore.

This ore, which is found in Cornwall, Hungary, and Siberia, occurs in masses, plates, threads, and crystallized in six-sided prisms, or four-sided pyramids, joined base to base.

Colour bluish grey. Streak brighter grey. Lustre metallic. Hardness 4 to 7. Sp. gr. 5.452 to 5.659; sometimes low as 4.129. Detonates with nitre.

Before the blow-pipe it melts easily; and while in fusion exhibits a green peach, which, on cooling, is covered with a brown crust. Tinges borax green.

Werner makes two varieties of this ore: the first he Copper calls compact from its fracture; and the second, for the same reason, he calls foliated. This last is somewhat darker coloured than the first, but in other respects they agree.

**Species 2. Copper pyrites**.

*Yellow copper ore.*

This ore, which is probably nothing else than sulphur of iron combined with copper, and which, therefore, would be more properly placed among iron ores, is found frequently in copper mines, and mixed with common pyrites or sulphuric of iron. It is sometimes amorphous, and sometimes crystallized. Its crystals are either three or four sided pyramids applied base to base, or six-sided plates.

Its colour is yellow; often tarnished. Its internal lustre metallic. Hardness 6 to 7; sometimes 9. Brittle. Sp. gr. 4.314 to 4.084. Delagrates; but does not detonate with nitre.

Before the blow-pipe decrepitates; gives a greenish sulphureous smoke, and melts into a black mass, which tinges borax green. Does not effervescence with nitric acid.

**Species 3. Purple copper ore**.

This ore is found in masses, or plates, or disseminated; sometimes, also, it is crystallized in octahedrons. Colour various, but most commonly purple; internally reddish. Streak reddish and bright. Lustre metallic. Hardness 6 to 7. Brittle. Sp. gr. 4.956 to 4.984. Effervescence with nitric acid, and tinges it green. Delagrates with nitre. Before the blow-pipe melts readily, without smoke, vapour, or smell; but is not reduced. Tinges borax a bright green.

A specimen of this ore, analysed by Klaproth, contained:

- 58 copper, - 18 iron, - 19 sulphur, - 5 oxygen.

**Species 4. Grey copper ore**.

This ore is found in Cornwall, Saxony, Hungary, &c. It is often amorphous, but often also crystallized. The primitive form of its crystals is the regular tetrahedron; but, in general, either the angles or the edges, or both, are truncated or bevelled.

Colour steel grey; often tarnished, and then dark grey. Streak dark grey; sometimes reddish brown. Powder blackish; sometimes with a tint of red. Lustre metallic. Hardness 7 or 8. Very brittle. Sp. gr. 4.8048. Delagrates with nitre. Before the blow-pipe crackles, but at last melts, especially if assisted by borax. The bead gives a white smoke, without any particular smell; tinges borax yellow or brownish red, but does not unite with it.

A specimen of this ore from Creminitz, analysed by Klaproth, contained:

- 31 copper, - 14 silver, - 34 antimony, - 3 iron, - 11 sulphur.

---

*Napion*, in an ore from the valley of Lanzo, found copper, silver, and antimony, nearly in the same proportions, but more iron, and some arsenic. Savorelli, as Baron Born informs us, besides the ingredients of Klaproth's analysis, found some gold and mercury in grey copper ore; and Klaproth himself found lead in most of the other specimens which he examined.

**Genus III. Oxys of copper**.

**Species 1. Red oxyd of copper**.

*Florid red copper ore—Red copper glaist.*

This ore is found in Cornwall, and many other countries. It occurs in masses, disseminated, in scales, and *Kirwan* crystallized. The figure of its crystals is most commonly the regular octohedron.

Colour commonly cochineal red. Streak brick red. Lustre metallic. Transparency, when amorphous, generally 6; when crystallized, 3 or 4. Hardens from 4 to 7. Soluble with effervescence in nitric acid. Before the blow-pipe melts easily, and is reduced.

This ore was supposed to be composed of carbonic acid and red oxyd of copper; but a specimen, examined by Vaquelin, which consisted of pure crystals, contained no acid. It must therefore be considered as an oxyd of copper.

Werner has made three varieties of this ore, which, from their texture, he has denominated compact, foliated, and fibrous. The first is seldom or never found crystallized, and is opaque; the second occurs amorphous, crystallized, and in scales; the third is carmine, ruby, or umber red; and occurs always in short capillary crystals, or delicate flakes.

This ore sometimes contains a mixture of red oxyd of iron; it is then called brick red copper ore, copper malachite, or copper ochre.

This ore is sometimes mixed with bitumen. Its colour is then brownish black, and it is called pitch ore.

**Species 3. Green oxyd of copper**.

*Green sand of Peru.*

This ore, which was brought from Peru by Dombey, is a glassy green powder, mixed with grains of quartz. When thrown on burning coals, it communicates a green colour to the flame. It is soluble both in nitric and muriatic acids without effervescence. The solution is green. It was supposed to contain muriatic acid; but Vaquelin has discovered, that the appearance of this acid was owing to the presence of some common salt, which is accidentally mixed with the sand.

**Genus IV. Salts of copper**.

**Species 1. Blue carbonat of copper (d)**.

*Mountain blue—Azur de cuivre—Blue calc of copper—Kupfer lazur.*

This ore, which occurs in the copper mines of Siberia, Sweden, Germany, Hungary, Cornwall, &c., is either amorphous or crystallized. The crystals are small, and difficult to examine. According to Rome de Lille, their primitive form is an octahedron, the sides of which are isosceles triangles, and two of them more inclined than the others. Be that as it may, the crystals of blue carbonat of copper are often rhombooidal prisms, either regular, or terminated by dihedral summits.

Its colour is azure or smalt blue. Streak blue. Hardness... Order V. MINERALOGY.

It effervesces with nitric acid, and gives it a blue colour. Before the blow-pipe it blackens, but does not melt. Tinges borax green with effervescence.

The crystals, according to Pelletier, are composed of: - 66 - 70 copper, - 18 - 20 carbonic acid, - 8 - 10 oxygen, - 2 - 2 water.

Fontana first discovered that this ore contained carbonic acid gas.

Variety 1. Earthy blue carbonate.

Mountain blue.

This variety generally contains a mixture of lime. It is never crystallized; and sometimes is almost in the state of powder. Lustrous. Texture earthy.

Variety 2. Striated blue carbonate of copper.

Lustre glassy. Transparency, when crystallized, 2; when amorphous, 1. Texture striated; sometimes approaching to the foliated.

Species 2. Green carbonate of copper (x).

Oxygenated carbonate of copper—Malachite.

This ore is generally amorphous, but sometimes it is crystallized in four-sided prisms, terminated by four-sided pyramids.

Colour green. Lustre silky. Hardness 5 to 7. Brittle. Sp.gr. 3.571* to 3.653. Effervesces with nitric acid, and gives a blue colour to ammonia. Before the blow-pipe it decrepitates and blackens, but does not melt. Tinges borax yellowish green. It is composed of carbonic acid and green oxyd of iron.

Variety 1. Fibrous malachite.

Texture fibrous. Opaque when amorphous; when crystallized its transparency is 2. Colour generally grasps green.

Variety 2. Compact malachite.

Texture compact. Opaque. Colour varies from the dark emerald green to blackish green.

A specimen of malachite from Siberia, analysed by Klaproth, contained: - 58.0 copper, - 18.0 carbonic acid, - 12.5 oxygen, - 11.5 water.

This species is sometimes mixed with clay, chalk, and gypsum, in various proportions; it is then known by the name of:

Common mountain green.

Its colour is verdigris green. Lustre o. Transparency o to 1. Hardness 3 to 4. Brittle. Texture earthy. Effervesces feebly with acids. Before the blow-pipe it exhibits the same phenomena with malachite.

Species 3. Sulphate of copper.

For a description of this salt, see Chemistry, p. 648, in this Supplement.

Species 4. Arsenic of copper (x).

Olive copper ore.

This ore is found at Carrarach in Cornwall. It is generally crystallized in six-sided compressed prisms. Its colour is olive green. Streak sometimes straw coloured, sometimes olive green. Lustre glassy. Transparency metallic from 4 to 2. Fracture conchoidal. Hardness 4 to 7.

Before the blow-pipe decrepitates with an arsenical smoke, and melts into a grey coloured bead. This bead, fused with borax, leaves a button of pure copper.

Klaproth discovered that it was composed of oxyd of copper and arsenic acid.

Sometimes this ore is combined with iron. It then p. 29. crystallizes in cubes. These cubes are of a dark green colour; before the blow-pipe they froth, give out an arsenical smoke, and do not so quickly form a grey bead as the arsenical of copper.

Order VI. IRON ORES.

To describe the uses of iron, would be to write the history of every art and manufacture, since there is not one which is not more or less dependent upon this useful metal. Nor is its abundance inferior to its utility. It exists almost everywhere, and seems, as it were, the bond which connects the mineral kingdom together.

Genus I. ALLOYS OF IRON

Species 1. Native iron (x).

Native iron has been found in Siberia and in Peru iron in immeasurable masses, which formed as if they had been fused. These masses evidently did not originate in the place where they were found. See First Balls, Suppl.

Colour bluish white. Fracture hackly. Lustre metallic. Malleable. Magnetic. Hardness 8 to 9. Sp.gr. 7.8. Prout has discovered, that the native iron found in Peru is alloyed with nickel.

Genus II. SULPHURS OF IRON

Species 1. Common sulphur of iron (x).

Pyrites.

This mineral occurs very frequently both in ores and phantoms, mixed with other bodies, for instance in flints. It is common often amorphous, and often also crystallized. The primitive form of its crystals is either a regular cube or an octahedron. The varieties of its form hitherto described amount to 304; for a description of which we refer Honer's Pyritologia.

Its colour is yellow. Lustre metallic. Hardness 8 to 10. Brittle. Sp.gr. 3.44 to 4.6. Soluble in nitric acid with effervescence. Scarce soluble in sulphuric acid. Before the blow-pipe burns with a blue flame and a sulphurous smell, and leaves a brownish bead, which tinges borax of a smutty green.

Variety 1. Common pyrites.

Fracture uneven. Hardness 10. Decrepitates when heated. Emits a sulphurous smell when rubbed. Not magnetic. It occurs often in coal mines and in flints.

Variety 2. Striated pyrites.

Texture striated. Hardness 10. Not magnetic.

Variety 3. Capillary.

Colour often steel grey. Found in needle-form crystals. Uncommon. Not magnetic.

Variety 4. Magnetic pyrites.

Found in masses. Texture compact. Hardness 8, 9. Slightly magnetic. Seems to contain less sulphur than the other varieties.

In pyrites the proportion of the sulphur to the iron is variable, and this explains the variety of its crystalline forms.

Genus III. Sulphur of iron.

Kirwan, II. 131.—Fontana, Jour. de Phys. XI. 509.—Klaproth, Beiträge, II. 287.

Pallas, Phil. Trans. LXVI. 523.—Rubin de Celis, ibid. LXXVIII. 37.—See also Schreiber, Jour. de Phys. XLI. 3; and Stevin, Phil. Trans. LXIV. 461. Genus III. Carburet of Iron.

Species I. Plumbago.

Graphite of Werner.

This mineral is found in England, Germany, France, Spain, America, &c. It occurs in kidney-form lumps of various sizes. Its colour is dark iron grey or brownish black; when cut, bluish grey. Lustrous metallic, from 3 to 4. Opaque. Structure flatly. Texture fine grained. Hardness 4 to 5. Brittle. Sp. gr. from 1.987 to 2.089; after being soaked in water 2.15; after being heated 2.3; and when heated after that 2.41+. Feels somewhat greasy. Stains the fingers, and marks strongly. The use of this mineral when manufactured into pencils is known to every person.

Its composition was discovered by Scheele. When pure it contains 90 carbon, 10 iron.

But it is often exceedingly impure: A specimen, for instance, from the mine of Pluffier, in France, analysed by Vauquelin, contained 23 carbon, 2 iron, 38 silica, 37 alumina.

Genus IV. Iron combined with Silica.

Species I. Emery.

This mineral is commonly disseminated through other sediments, but sometimes in the East Indies it occurs in large masses.

Its colour is bluish-grey, greyish brown, or bluish black, often covered with a yellowish rind; internally it discovers red or purple spots. Lustre 1 or 0; in some parts 2; and metallic. Opaque. Hardness 1-2. Brittle. Sp. gr. 3.92+. Before the blow pipe it blackens and gives a smutty yellow tinge to borax.

According to Wiegble it contains:

95.6 silica, 4.3 iron.

99.9

Genus V. Oxys of Iron.

This genus is very extensive; for iron is much more frequently found in the state of an oxyd than in any other.

Species I. Black oxyd of iron.

Common magnetic iron stone—Blackish octahedral iron ore.

This species of ore is very common in Sweden; it is found also in Switzerland, Norway, Russia, &c. It occurs in masses, plates, grains, and crystallized. The primitive form of its crystals is a regular octahedron. Sometimes two opposite sides of the pyramids are trapeziums, which render the apex of the pyramid circular. Sometimes the crystals pass into rhombohedral parallelopipeds, and into dodecahedrons with rhombohedral faces.

Its surface is brownish-black; internally bluish grey. Powder black*. Streak bluish-grey, brighter. Lustrous metallic. Hardness 9 to 10. Brittle. Sp. gr. from 4.004 to 4.688+. Attracted by the magnet, and generally possessed of more or less magnetic virtue. To this species belongs the magnet. Before the blow pipe it becomes browner, but does not melt. Tinges borax dark green.

When pure it consists entirely of oxyd of iron; and this oxyd appears to contain from .15 to .24 oxygen, and from .76 to .85 iron$. Undoubtedly it consists of a mixture of iron in two different states of oxidation. It is often also mixed and contaminated with foreign ingredients.

There are two varieties of this ore. The first is what we have just described; the second is in the form of lead, and has therefore been called Magnetic lead*.

This substance is found in Italy, Virginia, St. Domingo, the East Indies, and in the lead of the river Don at Aberdeen in Scotland. It is black, very hard, magnetic. Sp. gr. about 4.6. Not altered by the blow pipe per se; melts into a black glass with potash, and into a green glass with microcosmic salt, both opaque†. It probably contains some silica, as Kirwan has supposed‡.

Species 2. Specular iron ore.

Per oligiste.

This ore is found abundantly in the island of Elba near Specula Tuscany. It is either in masses or crystallized. The iron ore primitive form of its crystals, and of its integrant molecules, is the cube*. The varieties hitherto observed amount to 7. These are the rhombohedral parallelopiped; the cube, with three triangular faces instead of two of its angles diagonally opposite; two fixed pyramids. Sometimes the angles at the bases, and sometimes the alternate edges of the pyramid; a polyhedron of 24 faces resembling a cube with three triangular faces for two angles diagonally opposite, and two triangles for the rest of its angles. For a description and figure of these varieties, we refer to Rome de Lisle† and Huy‡.

Colour fixed grey; often tarnished, and beautifully iridescent, reflecting yellow, blue, red. Streak red. Powder dark red. Lustrous metallic. Hardness 9 to 10. Not brittle. Sp. gr. 5.0116+ to 5.218+. Slightly magnetic. Little altered by the blow pipe. Tinges borax an obscure yellow.

This ore, according to Mr Mallet, is composed of:

66.1 iron, 21.2 oxygen, 10.7 water and carbonic acid, 2.0 lime.

The quantity of oxygen here stated is probably too small, owing to the unavoidable inaccuracy which results from the dry way of analysis which Mr Mallet followed.

Micaceous iron ore

Is generally considered as a variety of this species. Kirwan, however, supposes it to contain carbon, and to be a distinct species.

It is found in Saxony, and in the island of Elba, &c., generally in amorphous masses, composed of this fixed laminae. Colour iron grey. Streak bluish grey. Lustrous metallic. Opaque. Feel greasy. Hardness 5 to 7. Brittle. Sp. gr. from 4.5 to 5.07. Slightly magnetic. **Species 3. Laminated specular iron ore.**

*For agglutinate of Haury.*

This ore, which is found at Mont-d'or in Auvergne, was usually arranged under the last species; but has been separated from it, we think properly, by Mr Haury, because the form of its crystals is incompatible with the supposition that their primitive nucleus is a cube, as we have seen is the case with common specular iron ore. Its crystals are thin octagonal plates, bounded by six linear trapezoids, alternately inclined different ways.

Colour steel grey. Powder reddish black. Lustre metallic; surface polished. Fracture glassy. Very brittle. Haury supposes that this ore has been produced by fire, and accordingly has given it a name which denotes its origin.

**Species 4. Brown iron ore.**

This species of ore is found abundantly in Britain, particularly in Cumberland and Lancashire; and it is also very common in other counties. It consists of the brown oxyd of iron, more or less contaminated with other ingredients.

Its colour is brown. Its streak reddish brown. Sp. gr. from 3.4771 to 3.951. Before the blow pipe blackens, but does not melt. Tinges borax greenish yellow.

**Variety 1. Brown hematites.**

The name hematites (bloodstone) was probably applied by the ancients only to those ores which are of a red colour, and have some resemblance to clotted blood; but by the moderns it is applied to all the ores of iron which give a reddish coloured powder, provided they be of a fibrous texture.

Brown hematites occurs in masses of various shapes, and it is said also to have been found crystallized in five or fixed sided acute angled pyramids. Colour of the surface brown or black, sometimes iridescent; internally nut brown. Powder red. Texture fibrous. Hardness 8 to 10. Brittle. Sp. gr. 3.789 to 3.951. Not magnetic.

This variety has not been analysed, but it seems to consist of brown oxyd of iron, oxyd of manganese, and alumina.

**Variety 2. Compact brown iron ore.**

This variety occurs in masses of very various and often fantastic shapes.

Colour brown. Internal lustre metallic. Texture compact. Hardness 6 to 9. Brittle. Sp. gr. 3.4771 to 3.551.

**Variety 3. Brown Scaly iron ore.**

This variety is generally incumbent on other minerals. Colour brown. Lustre metallic. Stains the fingers, marks strongly. Feels unctuous. Texture foliated. Hardness 3 to 5. Brittle. So light as often to float on water.

**Variety 4. Brown iron ochre.**

This variety occurs both massive and disseminated. Colour from nut brown to orange. Lustre o. Strongly stains the fingers. Texture earthy. Hardness 3 to 4. When slightly heated reddens.

**Species 5. Red iron ore.**

Colour red. Streak blood red. Sp. gr. from 3.423 to 5.005. Before the blow pipe blackens, but does not melt. Tinges borax yellowish olive green. When digested in ammonia, it becomes black and often magnetic.

**Variety 1. Red hematites.**

Found in masses, and all the variety of forms of flabellites. Colour between brownish red and steel grey. Powder red. Internal lustre metallic. Texture fibrous. Hardness 9 to 10. Brittle. Sp. gr. 4.744 to 5.005.

When pure it consists of red oxyd of iron, but it often contains manganese and alumina.

**Variety 2. Compact red iron ore.**

Found massive and flabellitic; sometimes in crystals of various forms, but they seem to be only secondary; sometimes in columns like bafait.

Colour between brown red and steel grey. Stains the fingers. Lustre 1 to 5; often semiflattened. Texture compact. Hardness 7 to 9. Brittle. Sp. gr. 3.423 to 3.76. Sometimes invested with a rosy red ochre.

**Variety 3. Red ochre.**

Found sometimes in powder, sometimes indurated. Colour blood red. Stains the fingers. Lustre o. Texture earthy. Hardness 3 to 5. Brittle.

**Variety 4. Red scaly iron ore.**

This variety is generally found incumbent upon other iron ores. Colour between cherry red and steel grey. Stains the fingers. Lustre silky, inclining to metallic. Texture foliated. Feels unctuous. Hardness 3 to 4. Brittle. Heavy.

**Species 6. Argillaceous iron ore.**

Oxyd of iron combined or mixed with clay.

This ore is exceedingly common; and though it contains less iron than the species already described, it is, in this country at least, preferred to them, because the method of extracting pure iron from it is easier, or rather because it is better understood.

Colour most commonly dark brown. Streak red or yellowish brown. Sp. gr. from 2.673 to 3.471. Before the blow pipe blackens, and tinges borax olive green and blackish. It is composed of oxyd of iron, alumina, lime, silica in various proportions. It generally yields from 35 to 40 per cent. of iron.

**Variety 1. Common argillaceous iron ore.**

The minerals arranged under this variety differ considerably from each other in their external characters. They are found in masses of various shapes, and often form large strata.

Colour various shades of grey, brown, yellow, and red. Streak reddish yellow or dark red. Lustre o. Hardness from 3 to 8. Smell earthy when breathed upon.

**Variety 2. Columnar or scapiform iron ore.**

This variety is found in columns, adhering to each other, but easily separable. They are commonly incrusted, and their surface is rough. Colour brownish red. Streak dark red. Slightly stains the fingers. Lustre o. Adheres strongly to the tongue. Sound hollow. Feel dry. Texture earthy.

**Variety 3. Acinoid iron ore.**

This variety is found in masses, and is commonly lenticular. Colour generally brownish red. Lustre metallic, nearly. Texture granular. Hardness 5 to 9. Brittle. Iron Ores.

Variety 4. Nodular, or kidney-form iron ore.

*Etites or Eaglestone.*

This variety, which was mentioned by the ancients, is generally found under the form of a rounded knob, more or less resembling a kidney, though sometimes it is quadrangular; and it contains within it a kernel, which is sometimes loose, and sometimes adheres to the outside rind. Colour of the stone yellowish brown; of the kernel ochre yellow. Surface generally fouled with earth. Lustre of the rind metallic; of the kernel o. Hardness from 4 to 7. Brittle.

Variety 5. Pilliform or granular iron ore.

This variety occurs in rounded masses, from the size of a pea to that of a nut. Surface rough. Colour commonly dark brown. Streak yellowish brown. Hardness 5 to 6. Brittle.

The oolitic ore found at Creusot, near mount Cenis, belongs to this variety. It is composed of

- 50 lime, - 30 iron, - 20 alumina.

100

Species 7. Lowland iron ore.

This species of ore is supposed to consist of oxyd of iron, mixed with clay and phosphuret or phosphat of iron. It is called lowland ore, because it is found only in low grounds; whereas the last species is more commonly in high grounds; and is therefore called highland ore.

This ore occurs in amorphous masses, and also in grains or powder. Its colour is brown. Streak yellowish brown. Lustre o, or common. Texture earthy. Hardness 3 to 5.

Variety 1. Meadow lowland ore.

Colour blackish or yellowish brown: Both colours often meet in the same specimen. Found in lumps of various sizes, often perforated. Fracture compact. Moderately heavy.

Frequently yields from 32 to 38 per cent. of iron.

Variety 2. Swampy iron ore.

This variety is generally found under water. It is in lumps, which are commonly perforated or corroded, and mixed with sand. Colour dark yellowish brown, or dark nut brown. Hardness 3 to 4. Brittle. Sp. gr. 2.944. It often contains .36 of iron.

Variety 3. Morally iron ore.

This variety is found either in a loose form or in perforated lumps. Colour light yellowish brown. Stains the fingers. Hardness 3. Friable.

Genus VI. Salts of Iron.

Species 1. Sparry iron ore (g).

This ore is common in Germany, France, and Spain.

It is found sometimes in amorphous masses, and sometimes crystallized.

Its colour is white; but it becomes tarnished by exposure to the air, and then assumes various colours. Streak grey or white. External lustre often metallic; internal common or glassy. Transparency 1 or 2; sometimes o. Texture foliated. Fragments rhomboidal. Hardness 5 to 7. Brittle. Sp. gr. 3.6 to 3.810. Not magnetic. Soluble in acids with very little effervescence. Before the blow-pipe decrepitates, becomes brownish black, and magnetic; but is scarcely fusible. Tinges borax smutty yellow, with some effervescence.

This ore, as Bergman ascertained, consists of iron, manganese, lime, and carbonic acid.

One specimen, according to his analysis, contained

- 38 iron, - 24 manganese, - 38 carbonat of lime.

100

Another contained

- 22 iron, - 28 manganese, - 50 carbonat of lime.

100

Whether the iron be combined with the carbonic acid is still a disputed point. The crystals of this ore are rhomboidal parallelopipeds; which is precisely the form of carbonat of lime. This amounts nearly to a demonstration, that the carbonic acid is combined with the lime; and that, as Cronstedt and Haüy have supposed, this ore is merely carbonat of lime, contaminated with a quantity of the oxyds of iron and manganese.

Species 2. Arseniat of iron.

Mr Proult has discovered this ore in Spain. Its colour is greenish white. Its texture granular. Insoluble in water and nitric acid. When melted on charcoal, the arsenical acid escapes with effervescence.

Species 3. Sulphat of iron.

For a description of this salt, see Chemistry, p. 631, in this Suppl.

Order VII. Tin Ores (h).

Tin is employed to cover plates of iron and copper, and to silver the backs of looking glasses: It enters into the composition of pewter; and forms a very important article in dyeing.

Tin ores are by no means so common as the ores of the metals which we have already described. They are found only in the primitive mountains (i). Hence Werner supposes them to be the most ancient of all metallic ores. They occur most frequently in granite, sometimes in porphyry, but never in limestone.

Almost

(g) Kirw. II. 190.—Bergman, II. 184.—Bayen. Jour. de Phys. VII. 213.—Razowowyski, Mem. Lavoisier, 1783; p. 149.

(h) Geoffroy, Mem. Per. 1738, p. 103.—Moreau, Ann. de Chim. XXIV. 127.

(i) Geologists have divided mountains into three classes; primitive, secondary, and tertiary. The primitive occupy the centre of all extensive chains; they are the highest, the most rugged, and exhibit the most pointed tops. They are considered as the most ancient mountains of the globe.

The secondary mountains occupy the outside of extensive ranges. They are usually composed of strata, more or less inclined, and commonly rest against the sides of the primitive mountains.—The tertiary mountains are much smaller than the others, and are often solitary. We use the terms primitive, secondary, &c., merely as procr Almost the only tin mines known to Europeans are those of Cornwall, Devonshire, Saxony, Bohemia, Silesia, Hungary, Galicia; those of the island of Banca and the peninsula of Malacca in India; and those of Chili and Mexico in America.

**GENUS I. SULPHURES OF TIN.**

**SPECIES I. Sulphuret of tin and copper.**

* Tin pyrites.

Hitherto this ore has only been found in Cornwall. There is a vein of it in that county, in the parish of St Agnes, nine feet wide, and twenty yards beneath the surface. Its colour is yellowish grey, passing into the fleck grey. Not unlike grey copper ore. Lustrous metallic. Hardness 5 to 6. Very brittle. Sp. gr. 4.35. Before the blow pipe it melts easily, with a sulphurous smell, into a black bead, and deposits a bluish oxyd on the charcoal.

The composition of this ore, as Klaproth informs us, was first discovered by Mr Raspe. According to Klaproth's analysis, it is composed of:

- 34 tin, - 36 copper, - 25 sulphur, - 3 iron, - 2 earth.

---

**GENUS II. OXYDS OF TIN.**

**SPECIES I. Brown oxyd of tin.**

*Tinstone-Woodtin.*

This ore, which may be considered as almost the only ore of tin, occurs in masses, in rounded pieces, and crystallized. These crystals are very irregular. Hauss supposes, that their primitive form is a cube; but Rome de Lisle, with more probability, makes it an octahedron; and in this opinion Mr Day agrees with him. The octahedron is composed of two four-sided pyramids, applied base to base. The sides of the pyramids are isosceles triangles, the angle at the vertex of which is 70°, and each of the other angles 55°. The sides of the two pyramids are inclined to each other at an angle of 90°. This primitive form, however, never occurs, but crystals of tinstone are sometimes found, in which the two pyramids are separated by a prism. For a complete description of the varieties of the crystals of tinstone, we refer the reader to Rome de Lisle and Mr Day.

Its colour is commonly brown. Streak grey. Hardness 9 to 10. Sp. gr. 6.9 to 7.0. Brittle.

**Variety 1. Common tinstone.**

Colour dark brown; sometimes yellowish grey, and sometimes nearly white. Streak light grey. Somewhat transparent when crystallized. Hardness 10. Sp. gr. 6.9 to 6.97. Before the blow pipe it decrepitates, and on charcoal is partly reduced. Tinges borax white.

According to Klaproth, it is composed of:

- 77.5% tin, - 21.5% oxygen, - 0.5% iron, - 0.5% silica.

100%

**Variety 2. Woodtin.**

This variety has hitherto been found only in Cornwall. It occurs always in fragments, which are generally rounded. Colour brown; sometimes inclining to yellow. Streak yellowish grey. Opaque. Texture fibrous. Hardness 9. Sp. gr. 7.0. Before the blow pipe becomes brownish red; decrepitates when red hot, but is not reduced.

Klaproth obtained from it .63 of tin; and, in all probability, it is an oxyd of tin nearly pure.

---

**ORDER VIII. ORES OF LEAD.**

The useful purposes to which lead in its metallic state is applied, are too well known to require description. Its oxyds are employed in painting, in dyeing, and sometimes also in medicine.

Ores of lead occur in great abundance in almost every part of the world. They are generally in veins; sometimes in siliceous rocks, sometimes in calcareous rocks.

**GENUS I. SULPHURES OF LEAD.**

**SPECIES I. Galena, or pure sulphuret of lead.**

This ore, which is very common, is found both in masses and crystallized. The primitive form of its crystal is a cube. The most common varieties are the cube, lead, sometimes with its angles wanting, and the octahedron. Composed of two four-sided pyramids applied base to base. The summits of these pyramids are sometimes conical, and sometimes their solid angles are wanting.

Its colour is commonly bluish grey, like lead. Streak bluish grey and metallic. Lustrous metallic. Sometimes H h flints

---

I. PRIMARY MOUNTAINS.

1. Granite, 2. Gneiss, 3. Micaceous shistus, 4. Argillaceous shistus, 5. Syenite, 6. Porphyry, 7. Shiltose porphyry, 8. Quartz, 9. Primitive limestone,

II. SECONDARY MOUNTAINS.

1. Argillaceous shistus, 2. Rubble stone, 3. Secondary limestone, 4. Shiltose hornblende, 5. Grunstein, 6. Amygdaloid,

III. TERTIARY MOUNTAINS.

1. Trap, 2. Argillaceous shistus, 3. Stratified limestone, 4. Sandstone, 5. Breccia, 6. Coal, 7. Chalk, 8. Sulphat of lime, 9. Rock salt, 10. Ferruginous clay, 11. Potters earth. Ores of stains the fingers. Texture foliated. Fragments cabi- cal. Hardness 5 to 7; sometimes even 9. Brittle. Sp. gr. 6.884 to 7.786. Effervesces with nitric and muriatic acids. Before the blow-pipe decrepitates, and melts with a sulphurous smell; part sinks into the charcoal.

It is composed of from .45 to .83 lead, and from .086 to .16 of sulphur. It generally contains some silver, and sometimes also antimony and zinc.

Variety 1. Common galena.

This variety corresponds nearly with the above de- scription. Sp. gr. 7.051 to 7.786. Sometimes stains the fingers.

Compact galena.

Found only in amorphous masses. Texture compact, inclining to foliated. Hardness 6 to 8. Sp. gr. 6.886 to 7.444. Lustre common. Streak lead grey, brighter and metallic. Often feels greasy, and stains the fingers.

Species 2. Sulphuret of lead, with silver and antimony*.

Plumbiferous antimoniated silver ore.

Found in amorphous masses. Colour grey. Hard- ness 5 to 6. Brittle. Sp. gr. from 5.2 to 8.

Variety 1. Light grey silver ore.

Colour light bluish grey. Streak light bluish grey, and brighter. Lustre metallic. Texture compact. Be- fore the blow pipe partly evaporates, and leaves a silver bead on the charcoal, surrounded by yellow dust.

According to Klaproth, it contains

| Substance | Percentage | |-----------|-----------| | Lead | 48.06 | | Silver | 20.40 | | Antimony | 7.88 | | Sulphur | 12.35 | | Iron | 2.25 | | Alumina | 7.02 | | Silica | 2.25 |

98.09†

Variety 2. Dark grey silver ore.

Colour iron grey, verging on black. Powder black, and stains the fingers. Lustre o. Texture earthy.

According to Klaproth, it contains

| Substance | Percentage | |-----------|-----------| | Lead | 41.00 | | Antimony | 21.50 | | Silver | 29.25 | | Sulphur | 22.00 | | Iron | 1.75 | | Alumina | 1.00 | | Silica | .75 |

97.25†

Species 3. Blue lead ore*.

This ore, which is found in Siberia, Germany, and Hungary, and is very rare, occurs sometimes in masses, and sometimes crystallized in six-sided prisms.

Colour between indigo blue and lead grey; sometimes inclining to black. Internal lustre metallic. Streak brighter. Texture compact. Hardness 6. Sp. gr. 5.461†. Before the blow pipe melts with a low blue flame and a sulphurous smell, and is easily reduced.

Species 4. Black lead ore†.

This ore, which is found in Germany and Brittany, and which is supposed to be common galena decayed, is sometimes in stalactites of various forms, and some- times crystallized in six-sided prisms, which are gener- ally truncated and confused.

Colour black, often with some streaks of red. Streak light bluish grey. Internal lustre metallic. Hardness 5 to 6. Brittle. Sp. gr. from 5.744 to 5.77*. Be- fore the blow-pipe decrepitates, melts easily, and is re- duced.

According to the experiments of Laumont, this ore is a sulphuret of lead (or rather sulphuret of oxyd of lead), mixed with some phosphat of lead.

Species 5. Sulphuret of lead, bismuth, and silver.

This ore, which occurs in the valley of Schapbach in of lead, bismuth, and silver.

Its colour is light bluish grey. Its lustre metallic. Its fracture uneven. Hardness 5. Melts easily before the blow pipe, emitting some smoke, and leaves a silver bead.

A specimen, analyzed by Mr Klaproth, contained

| Substance | Percentage | |-----------|-----------| | Lead | 33.0 | | Bismuth | 27.0 | | Silver | 15.0 | | Sulphur | 16.3 | | Iron | 4.3 | | Copper | 0.9 |

96.5†

Genus II. Oxyds of lead.

Species 1. Lead ochre †.

This ore, which is a mixture of the oxyd of lead ochre, with various earths, is found massive, and of various de- grees of hardness.

Its colour is either yellow, grey, or red. Lustre o. Transparency o to 1. Hardness 6 to 8; sometimes in powder. Sp. gr. from 4.165 to 5.545§. Texture com- pact. Effervesces with nitric and muriatic acids. Easily reduced by the blow-pipe, leaving a black flag, unless the lead be mixed with too great a proportion of earth.

Genus III. Salts of lead.

Species 1. Carbonat of lead ‡.

White lead spar.

This ore of lead, which is very common, is sometimes in masses, and sometimes crystallized. But the crys- talization is in general so confused, that the primitive form of the crystals has not yet been ascertained (x).

Its colour is white. External lustre, waxy or silky, from 3 to 1; internal 1 to 2. Generally somewhat transparent. Hardness 5 to 6. Brittle. Sp. gr. from 5.549 to 6.02§. Effervesces with nitric and muriatic acids when they are heated. Soluble in fat oils. Black- ened by sulphuret of ammonia *. Decrepitates when heated. Before the blow-pipe, in a silver spoon, it be- comes red by the yellow cone of the flame, while the blue cone renders it yellow†. On charcoal it is imme- diately reduced.

It contains from .60 to .85 of lead, and from .18 to .24 of carbonic acid. It is generally contaminated with carbonat of lime and oxyd of iron.

(x) See Hauy, Jour. de Min. No XXXI. 502, and Romé de Lisle, III. 380. Order IX.

Species 1. Phosphat of lead.

This ore, which is found in Siberia, Scotland, England, Germany, Carinthia, Brittany, &c., is sometimes amorphous, and sometimes crystallized. The primitive form of its crystals, according to Rome de Lisle, is a dodecahedron, consisting of a six-sided rectangular prism, terminated by fixed sided pyramids, the sides of which are isosceles triangles (l). Sometimes the pyramids are truncated, and even altogether wanting. The crystals of this ore are often acicular.

Its colour is commonly green; sometimes yellowish or brownish, or greyish white. Streak commonly greenish white. Powder yellowish. External lustre, waxy, 2 to 3. Somewhat transparent, except when its colour is greyish white. Hardness 5 to 6. Brittle. Sp. gr. from 6.86 to 6.47. Insoluble in water and sulphuric acid, and nearly insoluble in nitric acid; soluble in hot muriatic acid, with a slight effervescence. Before the blow-pipe it easily melts on charcoal, and crystallizes on cooling; with soda the lead is in some measure reduced.

The composition of this ore was first discovered by Gahn.

According to Fourcroy's analysis, a specimen from Erlenbach in Alsace, consists of:

- 96 phosphat of lead, - 2 phosphat of iron, - 2 water.

Or it contains:

- 79 oxyd of lead, - 1 oxyd of iron, - 18 phosphoric acid, - 2 water.

Species 2. Arseniat of lead.

This ore, which has hitherto been found only in Andalusia in Spain, and always in quartz or feldspar, is in small masses. Colour meadow green, often palting into wax yellow. Lustre waxy, 2. Transparency 2. Before the blow-pipe it melts, and retains its colour, and does not crystallize on cooling. When heated to whiteness, the arsenic acid escapes, and the lead is reduced.

Species 3. Phosphat and arseniat of lead.

Arsenic phosphat of lead.

This ore, which has been found in Auvergne in France, is either in masses, or crystallized in small six-sided prisms, with curvilinear faces.

Colour yellowish green, or shows alternate layers of pale and light green. Powder yellowish. The crystals are somewhat transparent; but when massive, this ore is opaque. Hardness 5 to 7. Brittle. Sp. gr. 6.846. Soluble in hot muriatic acid, but not in nitric. When heated it decrepitates. Before the blow-pipe melts easily, effervesces, emits a white smoke, with an arsenical smell. Some particles of lead are reduced, a brown fluid remains, which crystallizes on cooling like phosphat of lead.

According to Fourcroy, from whom the whole of this description has been taken, it is composed of:

- 65 arseniat of lead, - 27 phosphat of lead, - 5 phosphat of iron, - 3 water.

Species 4. Molybdat of lead.

This ore, which is found in Carinthia and at Leadhills in Scotland, was first mentioned in 1781 by Mr Jacquin (x). It occurs either in masses, or crystallized in cubic, or rhomboidal, or octahedral plates.

Its colour is yellow. Streak white. Lustre waxy. Generally somewhat transparent. Texture foliated. Fracture conchoidal. Hardness 5 to 6. Sp. gr. 5.486. When purified from its gangue by nitric acid, 5.706.

Soluble in fixed alkalies and in nitric acid. Communicates a blue colour to hot sulphuric acid. Soluble in muriatic acid, and decomposed by it. Before the blow-pipe decrepitates, melts into a yellowish grey mass, and globules of lead are reduced.

Klaproth first proved that this ore was molybdat of lead.

A very pure specimen, analysed by him, contained:

- 64.42 oxyd of lead, - 34.25 molybdic acid.

Species 5. Sulphat of lead.

This ore, which is found in Anglesey and in Andalusia, is generally crystallized. The crystals are regular octahedrons, and very minute.

Colour white. Lustre 4. Transparency 4. Before the blow-pipe it is immediately reduced.

The composition of this ore was first ascertained by Dr Withering.

Order IX. ORES OF ZINC.

Hitherto zinc has not been applied to a great variety of uses. It enters into the composition of brass; it is used in medicine; and Moreau has shown that its

(l) Crystal. III. 391. See also Haug's remarks on the same subject in the Jour. de Min. No XXXI, 306. (x) Kirw. II. 212.—Klaproth, Ann. de Chim. VIII. 103.—Hatchett, Phil. Trans. 1796, p. 285. (n) In his Miscellanea Aulricana, Vol. II. p. 139. Ores of oxyd might be employed with advantage as a white paint.

Ores of zinc are very abundant; they generally accompany lead ores, particularly galena. Calamine, or oxyd of zinc, has never been discovered in the primitive mountains.

**GENUS I. SULPHURES OF ZINC.**

**SPECIES 1. Common sulphuret of zinc.**

*Blende.*

This ore very commonly accompanies sulphuret of lead. It occurs both in amorphous masses and crystallized. The primitive form of its crystals is a rhomboidal dodecahedron, consisting of a six-sided prism, terminated by three-sided pyramids. All the faces of the crystals are equal rhombs. This dodecahedron may be mechanically divided into four equal rhomboidal parallelopipeds, and each of these into five tetrahedrons, whose faces are equal isosceles triangles. The figure of its integrant particles is the tetrahedron, similar to these.

The principal varieties of its crystals are the tetrahedron, the octahedron; the octohedron with its edges wanting; a 24-sided crystal, 12 of whose faces are trapezoids, and 12 elongated triangles; and, lastly, a 28-sided figure, which is the last variety, augmented by four equilateral triangles.

Colour yellow, brown, or black. Streak reddish, brownish, or grey. Lustre commonly metallic. Generally somewhat transparent. Texture foliated. Hardness 6 to 8. Sp. gr. 3.937 to 4.1665. Before the blow-pipe decrepitates, and gives out white flowers of zinc, but does not melt. Borax does not affect it. When breathed upon, loses its lustre, and recovers it very slowly.

**Variety 1. Yellow blende.**

Colour commonly sulphur yellow, often passing into olive green or brownish red. Powder pale yellow. Streak yellowish or reddish grey, not metallic. Lustre metallic. Transparency 2 to 4. Often phosphoresces when scraped or rubbed.

According to Bergman, it is composed of:

- 64 zinc, - 20 sulphur, - 5 iron, - 4 fluor acid, - 1 silica, - 6 water.

**Variety 2. Brown blende.**

Colour different shades of brown. Surface often tarnished. Powder brownish grey. Streak reddish or yellowish grey, not metallic. Lustre commonly metallic. Transparency 0 to 2.

A specimen of this variety, analysed by Bergman, contained:

- 44 zinc, - 17 sulphur, - 24 silica, - 5 iron, - 5 alumina, - 5 water.

**Variety 3. Black blende.**

Colour black, or brownish black; surface often tar-

nished blue; tips of the crystals often blood red. Powder brownish black. Streak reddish, brownish, or grey. Lustre common or metallic. Transparency 0 to 1; the red parts 2. Hardness 8.

A specimen of this variety, analysed by Bergman, contained:

- 52 zinc, - 26 sulphur, - 4 copper, - 8 iron, - 6 silica, - 4 water.

**GENUS II. OXYDS OF ZINC.**

**SPECIES 1. White oxyd of zinc.**

*Calamine.*

This ore is either found loose, or in masses, or crystallized. The primitive form of its crystals appears from the mechanical division of one of them by Mr. Haury, to be an octohedron composed of two four-sided pyramids, whose sides are equilateral triangles. But the crystals are minute, and their figure not very distinct. They are either four or six sided tables with bevelled edges, six-sided prisms, or three-sided pyramids.

Colour commonly white, grey, or yellow. Lustre often 0, sometimes 2 or 1. Opaque. The crystals are somewhat transparent. Hardness from 4 to 9, sometimes in powder. Sp. gr. from 2.585 to 3.074. When heated, becomes electric, without friction, like the tourmaline. Not blackened by sulphuret of ammonia. Soluble in sulphuric acid. Before the blow-pipe decrepitates, and does not melt.

This ore consists of oxyd of zinc more or less contaminated with iron, silica, lime, and other foreign ingredients. In one specimen Bergman found the following ingredients: 84 oxyd of zinc, 3 oxyd of iron, 12 silica, 1 alumina.

In another specimen, which gelatinized with acids, like zeolite, Klaproth found 66 oxyd of zinc, 33 silica.

In another specimen, analysed by Pelletier, the contents were:

- 52 silica, - 36 oxyd of zinc, - 12 water.

Mr. Kirwan has divided this species into three varieties.

**Variety 1. Friable calamine.**

In masses which easily crumble between the fingers. Lustre 0. Opaque. Texture earthy. When its colour is white, it is pure oxyd of zinc; when yellow, it is mixed with oxyd of iron. The white often becomes yellow when placed in a red heat, but resumes its colour on cooling. Common in China, where it is called wokan or ore of Tuttnago. Order X. MINERALOGY.

Variety 2. Compact calamine. Colour different shades of grey; sometimes yellow or brownish red. Lustre o. Opaque. Texture compact.

Variety 3. Striated calamine. This variety alone is found crystallized; but, like the others, it is also often amorphous. Colour white, and also various shades of grey, yellow, and red. Somewhat transparent. Texture striated. Lustre 2 to 1.

Genus III. Salts of Zinc. Species 1. Sulphate of zinc. For a description of this salt, we refer to Chemistry, n° 643. Suppl.

Order X. ORES OF ANTIMONY.

Antimony is much used to give hardness to those metals which otherwise would be too soft for certain purposes: printers types, for instance, are composed of lead and antimony. It is used also in medicine.

Ores of antimony are found abundantly in Germany, Hungary, France, Spain, Britain, Sweden, Norway, &c. They often accompany galena and hematites. They are found both in the secondary and primitive stratified mountains. Their gangue (o) is often quartz and sulphate of barytes.

Genus I. Alloys of Antimony. Species 1. Native antimony. This mineral, which was first discovered by Dr Swab, has been found in Sweden and in France, both in masses and kidney-shaped lumps. Colour white, between that of tin and silver. Lustre metallic. Texture foliated. Hardness 6. Sp. gr. above 6. Deflagrates with nitre. Before the blow-pipe melts and evaporates, depositing a white oxyd of antimony.

It consists of antimony, alloyed with 3 or 4 per cent. of arsenic.

Genus II. Sulphurets of Antimony. Species 1. Grey ore of antimony. This ore, which is the most common, and indeed almost the only ore of antimony, occurs both massive, disseminated, and crystallized. Its crystals are four-sided prisms, somewhat flattened, whose sides are nearly rectangles, terminated by short four-sided pyramids, whose sides are trapeziums. Sometimes two of the edges are wanting, which renders the prism fix-sided.

Colour grey. Lustre metallic. Streak grey, metallic, and brighter. Powder black or greyish black. Hardness 6 to 7. Sp. gr. from 4.1327 to 4.516. Often stains the fingers. Before the blow-pipe melts easily, burns with a blue flame, and deposits a white oxyd on the charcoal. When placed in an open vessel, over a slow fire, the sulphur evaporates, and leaves a grey oxyd of antimony. This oxyd, if fused with tartar, is reduced.

This ore, when taken out of the mine, almost always contains a large proportion of quartz or other stony matter. When pure, it is composed of about 74 antimony, 26 sulphur.

Werner has divided this species into three varieties.

Variety 1. Compact sulphuret. Colour bluish grey, surface often tarnished, and then it is blue or purplish. Lustre 1 to 2. Texture compact. Fracture fine grained, uneven. Powder black, dull, and earthy. Slightly stains the fingers.

Variety 2. Foliated sulphuret. Colour light steel grey. Lustre 3 to 4. Texture foliated. Powder as that of the last variety.

Variety 3. Striated sulphuret. Colour dark steel grey, and light bluish grey; surface often tarnished, and then it is dark blue or purplish. Lustre 3 to 2. Texture striated. Powder greyish black.

This variety alone has been hitherto found crystallized.

Species 2. Plumose antimonial ore. Sulphurets of antimony and arsenic. This species, which is sometimes found mixed with the crystals of sulphurated antimony, is in the form of brittle, capillary, or lasuginous crystals, often so small that they cannot be distinctly seen without a microscope.

Colour steel or bluish grey, often tarnished, and then brown or greyish black. Lustre 1, semimetallic. Before the blow-pipe emits a smoke, which deposits a whitish and yellowish powder on the charcoal; it then melts into a black slag.

It is supposed to consist of sulphur, antimony, arsenic, and some silver.

Species 3. Red antimonial ore. Hydrofulphuret of antimony. This species is generally found in cavities of sulphurated antimonial ore. It is crystallized in delicate needles, often diverging from a common centre.

Colour red. Lustre 2, silky. Sp. gr. 4-7. Before the blow-pipe melts easily, and evaporates with a sulphurous smell.

This ore has not been analysed. Mineralogists have supposed it to be a natural kerma. If so, we may conclude, from the experiments of Berthollet *, that it is * Ann. de Chim., xxv. composed of oxyd of antimony, sulphur, and sulphurated hydrogen gas.

Genus III. Oxys of Antimony. There is a substance found incumbent on sulphuret Oxys of antimony, of a yellow colour, and an earthy appearance, which has been supposed an oxyd of antimony, and denominated antimonial ochre. But hitherto it has not been analysed.

(o) The word gang is used by German mineralogists to denote a metallic vein. Now, it is not often that these veins consist entirely of ore; in general, they contain stony matter besides. For instance, in the copper mine at Airthrey, near Stirling, the copper ore is merely a narrow stripe in the middle of the vein, and the rest of it is filled up with sulphate of barytes. We use the word gangue (as the French do), to denote, not the metallic vein, but the stony matter which accompanies the ore in the vein. The gangue of the copper ore at Airthrey is sulphate of barytes. **Genus IV. Salts of Antimony.**

**Species I. Murat of antimony.**

This ore, which has been found in Bohemia, is sometimes in quadrangular tables; sometimes in acicular crystals grouped like zeolites; and sometimes in prisms.

Colour pale yellowish or greyish white. Lustre 3 to 4, nearly metallic. Transparency 2. Texture foliated.

Melts easily by the flame of a candle, and emits a white vapour. Before the blow pipe decrepitates; when powdered, and just ready to melt, it evaporates, and leaves a white powder around. Between two pieces of coal it is reducible to a metallic state.

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**Order XI. Ores of Bismuth.**

Bismuth is employed in the manufacture of pewter, of printers types, in soldering; and perhaps also its property of rendering other metals more fusible, might make it useful in anatomical injections. The quantity consumed in commerce is not great.

It has been found only in the primitive mountains, and is by no means common. When unaccompanied by any other metal, it does not form veins, but kidney-form masses. It often accompanies cobalt. Its gangue is commonly quartz. Its ores are not very abundant. They have been found chiefly in Sweden, Norway, Transylvania, Germany, France, and England.

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**Genus I. Alloys of Bismuth.**

**Species I. Native bismuth.**

This mineral, which is found at Schneeberg, Johanngeorgenstadt, &c., in Germany, has commonly the form of small plates lying above one another. Sometimes it is crystallized in four-sided tables, or indistinct cubes.

Colour white with a shade of red; surface often tarnished red, yellow, or purple. Lustre metallic, 3 to 2. Opaque. Texture foliated or striated. Hardness 6. Sp. gr. 9.022† to 9.57†. Exceedingly fusible. Before the blow-pipe gives a silvery white bead, and at last evaporates in a yellowish white smoke, which is deposited on the charcoal.

It is generally accompanied by cobalt, and sometimes contains arsenic.

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**Genus II. Sulphurets of Bismuth.**

**Species I. Common sulphuret of bismuth.**

This ore, which is found in Sweden, Saxony, and Bohemia, occurs sometimes in amorphous masses, and sometimes in needleform crystals.

Colour commonly bluish grey, sometimes white; surface often tarnished yellow, red, and purple. Powder black and shining. Lustre metallic, 2 to 3. Streak obscurely metallic. Texture foliated. Hardness 5. Brittle. Sp. gr. 6.131† to 6.467†. When held to the flame of a candle, it melts with a blue flame and sulphureous smell. Before the blow-pipe emits a reddish yellow smoke, which adheres to the charcoal. This powder becomes white when it cools, and resumes its former colour when the flame is directed upon it.

This ore, according to Sage, contains 60 bismuth, and, according to La Perouse, it holds 36 sulphur.

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**Genus III. Oxys of Bismuth.**

**Species I. Yellow oxyd of bismuth.**

Bismuth ochre.

This ore generally accompanies the two species already described. It is found in two states; either of an earthy consistence, or crystallized in cubes or quadrangular plates.

Colour usually greenish yellow, sometimes grey. Soluble in nitrous acid without effervescence, and may in a great measure be precipitated by the effusion of water.

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**Order XII. Ores of Arsenic.**

Arsenic is used as an alloy for several other metals, especially copper. It is sometimes employed to facilitate the fusion of glass, or to render it opaque, in order to form an enamel. Preparations of arsenic are employed as paints; and, like most other violent poisons, it has been introduced into medicine.

This metal is scattered in great abundance over the mineral kingdom, accompanying almost every other metal, and forming also sometimes peculiar veins of its own. Of course it occurs in almost every species of mountain, and is accompanied by a variety of gangues.

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**Genus I. Alloys of Arsenic.**

**Species I. Native arsenic.**

This mineral is found in different parts of Germany. It occurs generally in masses of various shapes, kidney-form, botryoidal, &c.

Colour that of steel. Its surface quickly becomes tarnished by exposure to the air. Lustre metallic (when fresh), 3 to 2. Streak bluish grey, metallic, and bright. Powder dull and black. Texture compact. Hardness 7 to 8. Brittle. Sp. gr. 5.67† to 5.7249†. Gives an arsenical smell when struck. Before the blow-pipe emits a white smoke, diffuses a garlic smell, burns with a blue flame, gradually evaporates, depositing a white powder.

It is always alloyed with some iron, and often contains silver, and sometimes gold.

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**Genus II. Sulphurets of Arsenic.**

**Species I. Orpiment (p).**

*Arupigmentum.*

This ore, which is found in Hungary, Wallachia, Georgia, and Turkey in Asia, is either malleable or crystallized. The crystals are confused, and their figure cannot be easily determined; some of them appear octahedrons, and others minute four-sided prisms.

Its colour is yellow. Streak orange yellow. Lustre waxy, 2 to 3. Transparency from 0 to 2. Texture foliated. Hardness 4 to 8. Sp. gr. from 3.0048* to 3.524†. Effervesces with hot nitric acid. Burns with... XIII. MINERALOGY.

A bluish white flame. Before the blow-pipe melts, smokes, and evaporates, leaving only a little earth and some traces of iron.

Composed of: - 80 sulphur, - 20 arsenic.

100

Species 2. Realgar*.

This mineral is found in Sicily, about Mount Vesuvius, in Hungary, Transylvania, and various parts of Germany. It is either massive or crystallized. The primitive form of the crystals is, according to Romé de Lisle, a four-sided rhombohedral prism, terminated by four-sided pyramids, the sides of which are rhombs†. It commonly appears in 4, 6, 8, 10, or 12 sided prisms, terminated by four-sided summits‡.

Colour red. Streak yellowish red. Powder scarlet. Lustre 3 to 2. Transparency from 2 to 3; sometimes c. Hardness 5 to 6. Sp. gr. 3.3384§. It is an electric per se, and becomes negatively electric by friction†. Nitric acid deprives it of its colour. Before the blow-pipe it melts easily, burns with a blue flame and garlic smell, and soon evaporates.

Composed of: - 20 sulphur, - 80 arsenic.

100

Genus III. Oxyds of Arsenic.

Species 1. White oxyd of arsenic*.

Native calx of arsenic.

This ore is found in various parts of Germany, Hungary, &c., either in powder, or massive, or crystallized in prismatic needles.

Colour white or grey, often with a tint of red, yellow, green, or black. Lustre common, 1 to 2. Transparency 1 to 3; when crystallized, 2. Texture earthy. Hardness 6. Brittle. Sp. gr. 3.74. Soluble in hot diluted nitric acid without effervescence. Soluble at 60° Fahrenheit in 80 times its weight of water. Before the blow-pipe sublimes, but does not inflame. Tinges borax yellow.

Order XIII. COBALT ORES.

Cobalt is employed to tinge glas of a blue colour, and is useful in painting upon porcelain.

Cobalt ores are found almost exclusively in the stratified mountains, except one species, sulphuret of cobalt, which affects the primitive mountains. They are not very abundant; and for that reason cobalt is more valuable than many of the other metals which have been already treated of. They are commonly accompanied by nickel, bismuth, or iron. They are most abundant in Germany, Sweden, Norway, and Hungary; they have been found also in Britain and France, but not in any great quantity.

Genus I. Alloys of Cobalt.

Species 1. Cobalt alloyed with arsenic†.

Dull grey cobalt ore.

This ore, which occurs in different parts of Germany, is either amorphous or crystallized. The forms of its crystals are the cube; sometimes the cube with its angles, or edges, or both wanting; and the octahedron‡.

Its colour, when fresh broken, is whitish or bluish metallic grey, sometimes with a shade of red; when exposed to the air it soon becomes tarnished. Streak bluish grey and metallic. Lustre scarcely metallic, 0 to 1. Texture compact. Hardness 10. Difficulty frangible. Sp. gr. when amorphous, 5.309 to 5.571§; when crystallized 7.7207†. When struck it gives out an arsénical smell. Before the blow-pipe it gives out an arsénical vapour, becomes magnetic, and melts easily, unless it contains a great quantity of iron. Tinges borax dark xxxii. 588, blue, and a small metallic bead is obtained.

A specimen of this ore from Cornwall, examined by Mr Klaproth, contained: - 20 cobalt, - 24 iron, - 33 arsenic,

77

with some bismuth and stony matter*.

Another specimen from Tunaberg, according to the analysis of the same chemist, contained: - 55.5 arsenic, - 44.0 cobalt, - .5 sulphur.

100†

Genus II. Sulphurets of Cobalt.

Species 1. White cobalt ore †.

Sulphuret of cobalt, arsenic, and iron.

The descriptions which different mineralogists have given of this ore are so various, that it is impossible not to suppose that distinct substances have been confounded together.

It occurs either in masses, or crystallized in cubes, dodecahedrons, octahedrons, and icosahedrons.

Colour tin white; sometimes tarnished reddish or yellowish. Powder steel grey. Lustre partly metallic, and from 2 to 4; partly 0 or 1. Texture foliated. Hardness 8 to 9. Sp. gr. from 6.284† to 6.4509‡. Before the blow-pipe generally gives out an arsénical vapour, and does not melt.

The analyses that have been given of this ore are very various. Sometimes it has been found to contain no arsenic nor iron, and sometimes to contain both. A specimen from Tunaberg in Sweden, which ought to belong to this species, was analyzed by Taffert, and found to consist of: - 49 arsenic, - 36.6 cobalt, - 5.6 iron, - 6.5 sulphur.

97.8†

Klaproth found a specimen of the same ore to contain: - 55.5 arsenic, - 44.0 cobalt, - .5 sulphur.

100‡

Genus III. Oxyds of Cobalt.

Species 1. Black cobalt ore or ochre§.

This ore, which occurs in different parts of Germany, is either in the form of a powder, or indurated.

Colour black, often with a shade of blue, grey, brown, or green. Lustre 0 to 1. Streak brighter. Hardness 3.5 (of the indurated) from 4 to 8. Sp. gr. 3 to 4. Soluble in muriatic acid. Tinges borax blue. Species 2. Brown cobalt ore*. Colour greyish or dark leather brown. Streak brighter, unctuous. Communicates a pale blue tinge in fusion.

Species 3. Yellow cobalt ore†. Colour yellow. Dull and earthy. Hardness 4 to 5. Texture earthy. Streak brighter, unctuous. Gives a weak blue tinge.

Genus IV. Salts of Cobalt.

Species 1. Arsenic of cobalt‡. Red cobalt ore.

This species, like most other ores of cobalt, has neither been accurately described nor analyzed.

It is found in masses of various shapes, and crystallized in quadrangular tables or acicular prisms.

Colour red. Lustre from 2 to 3, sometimes 0. Transparency 0 to 2. Hardness 5 to 7. Brittle. Before the blowpipe becomes blackish grey. Diffuses a weak arsenical smell. Tinges borax blue.

Order XIV. Ores of Nickel.

Hitherto nickel has been found in too small quantities to be applied to any use; of course there are, properly speaking, no mines of nickel. It occurs only (as far as is yet known) in the secondary mountains, and it commonly accompanies cobalt. It has been found in different parts of Germany, in Sweden, Siberia, Spain, France, and Britain.

Genus I. Sulphurets of Nickel.

Species 1. Sulphuret of nickel with arsenic and iron. Kupfer nickel*.

This, which is the most common ore of nickel, occurs either massive or disseminated, but never crystallized.

Colour often that of copper, sometimes yellowish white or grey. Recent fracture often silver white. Lustre metallic, 2 to 3. Texture compact. Hardness 8. Sp. gr. 6.6886 to 6.6481‡. Soluble in nitric and nitro-muriatic acids. Solution green. Before the blowpipe exhales an arsenical smoke, and melts into a bead which darkens by exposure to the air.

It is composed of various proportions of nickel, arsenic, iron, cobalt, sulphur; often contains bismuth, and sometimes silver and copper.

Genus II. Oxys of Nickel.

Species 1. Nickel ochre*. This mineral occurs either in the form of a powder, or indurated, and then is either amorphous, or crystallized in acicular form crystals. The powder is generally found on the surface of other nickel ores.

Colour different shades of green. Lustre 1 to 0. Texture earthy. Sp. gr. considerable. Slowly dissolves in acids; solution green. Before the blowpipe does not melt; but gives a yellowish or reddish brown tinge to borax.

This ore often contains sulphate of nickel, which is soluble in water. The solution, when evaporated, gives oblong rhombohedral crystals, from which alkalies precipitate a greyish green oxyd. This oxyd is soluble by acids and by ammonia. The acid solution is green; the alkaline blue.

Genus III. Salts of Nickel.

Species 1. Arsenic of nickel†.

This ore, which was lately discovered at Regendorf in Austria by Mr Gmelin, is found in shapeless masses, and is often mixed with plates of sulphate of barytes.

Colour pale grey, here and there mixed with pale green. Streak white. Lustre 0. Texture compact. Hardness 7. Difficulty frangible. Sp. gr. considerable. Adheres slightly to the tongue, and gives an earthy smell when breathed on. Soluble in hot nitric and muriatic acids; solution green.

Contains some cobalt and alumina.

Order XV. Ores of Manganese (q).

Hitherto manganese, in its metallic state, has scarcely been put to any use; but under the form of an oxyd it has become of great importance. The oxyd of manganese has the property of rendering colourless a variety of bodies which injure the transparency of glass; and it has been long used in glass manufactories for this purpose under the name of glass soap. By means of the same oxyd, oxy-muriatic acid is prepared, which has rendered manganese of great importance in bleaching. Not to mention the utility of manganese to the chemist, the property which it has of facilitating the oxidation of other metals, and of rendering iron more fusible—will probably make it, in no very remote period, of very considerable importance in numerous manufactories.

Ores of manganese occur often in strata, both in the primitive and secondary mountains; scarcely ever, however, we believe, in those mountains which are considered as the most ancient of all. They are very common, having been found abundantly in Germany, France, Spain, Britain, Sweden, Norway, Siberia, and other countries.

Genus I. Oxys of Manganese.

Hitherto manganese has only been found in the state of oxyd. La Perouse, indeed, suspected that he had found it in a metallic state; but probably there was some mistake or other in his observations.

Species 1. Oxyd of manganese combined with barytes. This species, which exists in great abundance in Romanche near the river Soane in France, is found massed in five, forming a stratum in some places more than 12 feet thick.

Colour greyish black or brownish black, of great intensity. Lustre external, 0; internal, metallic, 1. Soon tarnishes by exposure to the air, and then becomes intensely black. Texture granular. Fracture uneven; sometimes conchoidal. Often porous. Hardness 11. Difficulty frangible. Sp. gr. from 3.950 to 4.10. Absorbs water. When taken out of water after a minute's immersion, it has a strong argillaceous smell. Conducts electricity nearly as well as if it were in a metallic state. Insoluble by the blowpipe. Tinges soda red; the colour disappears before the blue cone of flame, and is reproduced by the action of the yellow flame.

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(a) Pott, Min. Berol., VI. 40.—Müller, Mem. Berlin, 1773, p. 3.—La Perouse, Jour. de Phys. XVI. 156, and XV. 67, and XXVIII. 68.—Sage, Mem. Par. 1785, 235. From the analysis of Vauquelin, it appears that it is composed of:

- 50.0 white oxyd of manganese, - 33.7 oxygen, - 14.7 barytes, - 1.2 silica, - 4 charcoal.

This ore occurs both massive and disseminated; it is also sometimes crystallized in slender four-sided prisms or needles.

Colour usually dusky steel grey; sometimes whitish grey, or reddish grey. Streak and powder black. External lustre 3 to 2; internal metallic, 2 to 1. Texture striated or foliated. Hardness 4 to 5. Brittle. Sp. gr. from 4.073 to 4.8165. Before the blow-pipe darkens: tinges borax reddish brown.

A specimen of oxyd of manganese from the mountains of Voges, which probably belonged to this species, and which was analysed by Vauquelin, was composed of:

- 82 oxyd of manganese, - 7 carbonat of lime, - 6 silica, - 5 water.

Sometimes it contains a little barytes and iron.

Species 3. Black or brown ore of manganese.

This ore is found sometimes in the state of powder, and sometimes indurated in amorphous masses of various figures. Colour either black, sometimes with a shade of blue or brown; or reddish brown. Streak of the harder forms metallic; of the others, black. Lustre 0 to 1; internal (when it is indurated), metallic. Texture compact. Hardness 5 to 7. Sp. gr. 3.7076 to 3.9030; that of the powdery sometimes only 2. Before the blow-pipe it exhibits the same phenomena as the last species.

A specimen of this ore, analysed by Weftrum, contained:

- 45.00 manganese, - 14.00 oxyd of iron, - 11.00 silica, - 7.25 alumina, - 2.00 lime, - 1.50 oxyd of copper, - 18.00 air and water.

Genus II. Salts of manganese.

Species 1. Carbonat of manganese.

White ore of manganese.

This species occurs in Sweden, Norway, and Transylvania. It is either in the form of loose scales, or massive, or crystallized in needles.

Colour white, or reddish white. Texture either radiated or scaly. Lustre of the scaly 2. Transparency 1 to 2. Hardness of the massive 6 to 9. Sp. gr. 2.794. Effervesces with mineral acids. Heated to redness, blackens. Tinges borax violet.

Suppl. Vol. II. Part I.

Species 2. Red ore of manganese.

Carbonat of manganese and iron.

This species has been found in Piedmont and in the Pyrenees. It is sometimes in powder, sometimes massive, sometimes crystallized in rhombohedral prisms or manganese needles.

Colour pale rosy red, mixed with white. Powder nearly white. Lustre c. Transparency r. Hardness Min. 7 to 8. Sp. gr. 3.233. Effervesces with nitric and muriatic acids. When heated to redness becomes reddish brown. Tinges borax red.

A specimen, analysed by Ruprecht, contained:

- 55 silica, - 35 oxyd of manganese, - 7 oxyd of iron, - 1.5 alumina.

98.5

Order XVI. Ores of tungsten.

As no easy method has hitherto been discovered of reducing tungsten to a metallic state, we need not be surprised that it has been applied to no use. Ores of tungsten are by no means common. They have hitherto been found only in the primitive mountains. Their gangue is commonly quartz. They very often accompany tin ores.

Genus I. Oxyds of tungsten.

Species 1. Wolfram.

Oxyds of tungsten, iron, and manganese—Tungstic acid of iron and manganese.

This species is found in different parts of Germany, in Sweden, Britain, France, and Spain; and is almost constantly accompanied by ores of tin. It occurs both massive and crystallized. The primitive form of its crystals, according to the observations of Mr Haug, is a rectangular parallelopiped, whose length is 8.66, whose breadth is 5, and thickness 4.33. It is not common, however, to find crystals of this perfect form; in many cases, the angles, and sometimes the edges, of the crystal are wanting; owing, as Mr Haug has shewn, to the superposition of plates, whose edges or angles decrease according to a certain law.

Colour brown or brownish black. Streak reddish brown. Powder stains paper with the same colour. Lustre external, 2; internal, 2 to 3; nearly metallic. Texture foliated. Easily separated into plates by percussion. Hardness 6 to 8. Sp. gr. from 7.006 to 7.333. Moderately electric by communication. Not magnetic. Insoluble by the blow-pipe. Forms with borax a greenish globule, and with microcosmic salt a transparent globule of a deep red.

The specimen of this ore examined by Messrs d'El. Jour. de Min., was composed of 65 oxyd of tungsten, 22 oxyd of manganese, 13 oxyd of iron.

Another Another specimen from Pays le Mines in France, analysed by Vauquelin and Hecht, contained:

- 67.00 oxyd of tungsten, - 18.00 black oxyd of iron, - 6.25 black oxyd of manganese, - 1.50 silica, - 7.25 oxyd of the iron and manganese.

100.00 $

GENUS II. SALTS OF TUNGSTEN.

SPECIES I. Tungstic of lime (s).

Tungsten.

This ore, which is now exceedingly scarce, has hitherto been found only in Sweden and Germany. It is either massive or crystallized; and, according to Haüy, the primitive form of its crystals is the octohedron.

Colour yellowish white or grey. Lustre 3 to 2. Transparency 2 to 3. Texture foliated. Hardness 6 to 9. Sp. gr. 5.8 to 6.0665. Becomes yellow when digested with nitric or muriatic acids. Insoluble by the blow-pipe. With borax forms a colourless glass, unless the borax exceed, and then it is brown. With microcosmic salt it forms a blue glass, which loses its colour by the yellow flame, but recovers it in the blue flame.

It is composed of about 70 oxyd of tungsten, 30 lime.

100

with a little silica and iron.

SPECIES 2. Brown tungstic.

This ore is found in Cornwall, and is either massive or composed of small crystalline grains.

Colour grey, variegated with yellow and brown. Lustre 2, waxy. Hardness 6 to 7. Sp. gr. 5.57. Its powder becomes yellow when digested in aqua regia.

According to Klaproth, it is composed of:

- 88 oxyd of tungsten, - 11.5 lime.

99.5

ORDER XVII. ORES OF MOLYBDENUM.

If ever molybdenum be found in abundance, it will probably be useful in dyeing and painting. At present it is very scarce, having only been found in Sweden, Germany, Carniola, and among the Alps. Like tin and tungsten, it affects the primitive mountains.

GENUS I. SULPHURET OF MOLYBDENUM.

SPECIES I. Common sulphuret (r).

Molybdene.

This ore, which is the only species of molybdenum ore at present known, is found commonly massive; sometimes, however, it is crystallized in hexahedral tables.

Colour light lead grey; sometimes with a shade of red. Streak bluish grey, metallic. Powder bluish. Lustre metallic, 3 to 2. Texture foliated. Lamellae slightly flexible. Hardness 4. Sp. gr. 4.569 to 4.7385. Feels greasy; stains the fingers. Marks bluish black. A piece of resin rubbed with this mineral becomes positively electric. Insoluble in sulphuric and muriatic acids; but in a boiling heat colours them green. Effervesces with warm nitric acid, leaving a grey oxyd undissolved. Before the blow-pipe, on a silver spoon, emits a white smoke, which condenses into a white powder, which becomes blue in the external, and loses its colour in the external, flame. Scarcely affected by borax or microcosmic salt. Effervesces with soda, and gives it a reddish pearl colour.

Composed of about 60 molybdenum, 40 sulphur.

ORDER XVIII. ORES OF URANIUM.

Uranium has hitherto been found only in Germany, and has not been applied to any use. The only two mines where it has occurred are in the primitive mountains.

GENUS I. OXYDS OF URANIUM.

SPECIES I. Sulphuret of uranium (†).

Pechblende.

This ore, which has been found at Johanngeorgenstadt in Saxony, and Joachimsthal in Bohemia, is either massive or stratified with other minerals.

Colour black or brownish black; sometimes with a shade of grey or blue. Streak darker. Powder opaque and black. Lustre semimetallic, from 3 to 4. Fracture conchoidal. Hardness 7 to 8. Very brittle. Sp. gr. from 6.3785 to 7.55, and even higher. Imperfectly soluble in sulphuric and muriatic acids; perfectly insoluble in nitric acid and aqua regia. Solution wine yellow. Insoluble with alkalies in a crucible; insoluble by the blow-pipe per se. With borax and soda forms a grey glassy opaque flag; with microcosmic salt, a grey glass.

Composed of oxyd of uranium and sulphur, and mixed with iron and silica, and sometimes lead.

A specimen of this ore from Joachimsthal, analysed lately by Klaproth, contained:

- 86.5 uranium, - 6.0 sulphuret of lead, - 5.0 silica, - 2.5 oxyd of iron,

100.00 $

SPECIES 2. Yellow oxyd of uranium (‡).

Uranitic ochre.

This ore is generally found on the surface of the last species at Johanngeorgenstadt, and is either massive or in powder.

Colour yellow, red, or brown. Streak of the yellow forts yellow; of the red, orange yellow. Lustre o. Slightly stains the fingers. Feels meagre. Texture earthy. Hardness 3 to 4. Sp. gr. 3.2438. Insoluble by the blow-pipe; but in a strong heat becomes brownish grey.

Composed of oxyd of uranium and oxyd of iron.

Genus Genus II. Salts of Uranium.

Species 1. Carbonat of uranium.

This substance is also found at Johannisgeorgenstadt, near Eibenstock and Rheinbreitenbach. It is sometimes amorphous, but more commonly crystallized. Its crystals are square plates, octahedrons, and six-sided prisms.

Colour green; sometimes nearly white; sometimes, though rarely, yellow. Streak greenish white. Lustre 3 to 2; internal, 2; sometimes pearly; sometimes nearly metallic. Transparency 2 to 3. Texture foliated. Hardness 5 to 6. Brittle. Soluble in nitric acid without effervescence. Insoluble by alkalis.

Composed of carbonat of uranium, with some oxyd of copper. When its colour is yellow it contains no copper.

Order XIX. Ores of Titanium.

Titanium has been known for so short a time, and its properties are yet imperfectly ascertained, that many of its uses must remain to be discovered. Its oxyd, as we learn from Mr Darcey, has been employed in painting on porcelain. Hitherto it has been found only in the primitive mountains, the Crapacks, the Alpes (v), and the Pyrenees. It has been found also in Brittany and in Cornwall.

Genus I. Oxys of Titanium.

Species 1. Red oxyd of titanium.

Red fleur—Sagamite.

This ore has been found in Hungary, the Pyrenees, the Alpes, and in Brittany in France. It is generally crystallized. The primitive form of its crystals, according to the observations of Mr Haüy, is a rectangular prism, whose base is a square; and the form of its molecules is a triangular prism, whose base is a right angled isosceles triangle, and the height is to any of the sides of the base about the right angle as \( \sqrt{2} : \sqrt{3} \), or nearly as 3 : 4. Sometimes the crystals of titanium are six-sided, and sometimes four-sided, prisms, and often they are implicated together.

Colour red or brownish red. Powder brick or orange red. Lustre 3. Transparency commonly 0; sometimes 1. Texture foliated. Hardness 9. Brittle. Sp.gr. from 4.18* to 4.2469†. Not affected by the mineral acids. When fused with carbonat of potash, and diluted with water, a white powder precipitates, heavier than the titanium employed. Before the blow-pipe it does not melt, but becomes opaque and brown. With microcosmic salt it forms a globule of glass, which appears black; but its fragments are violet. With borax it forms a deep yellow glass, with a tint of brown. With soda it divides and mixes, but does not form a transparent glass.

When pure, it is composed entirely of oxyd of titanium.

Species 2. Menachanite (x).

Oxyd of titanium combined with iron.

This substance has been found abundantly in the valley of Menachan in Cornwall; and hence was called menachanite by Mr Gregor, the discoverer of it. It is in small grains, like gunpowder, of no determinate shape, and mixed with a fine grey sand. Colour black. Easily pulverized. Powder attracted by the magnet. Sp.gr. 4.427. Does not detonate with nitre. With two parts of fixed alkali it melts into an olive coloured mass, from which nitric acid precipitates a white powder. The mineral acids only extract from it a little iron. Diluted sulphuric acid, mixed with the powder, in such a proportion that the mass is not too liquid, and then evaporated to dryness, produces a blue coloured mass. Before the blow pipe does not decrepitate nor melt. It tinges microcosmic salt green; but the colour becomes brown on cooling; yet microcosmic salt does not dissolve it. Soluble in borax, and alters its colour in the same manner.

According to the analysis of Mr Gregor, it is composed of:

- 46 oxyd of iron, - 45 oxyd of titanium, - 0.1 with some silica and manganese.

According to Mr Klaproth's analysis, it is composed of:

- 51.00 oxyd of iron, - 45.25 oxyd of titanium, - 3.50 silica, - 2.25 oxyd of manganese.

A mineral, nearly of the same nature with the one just described, has been found in Bavaria. Its specific gravity, however, is only 3.7. According to the analysis of Vauquelin and Hecht, it is composed of:

- 49 oxyd of titanium, - 35 iron, - 2 manganese, - 14 oxygen combined with the iron and manganese.

Species 3. Calcareo siliceous ore of titanium.

Oxyd of titanium combined with lime and silica—Titanite.

This ore has hitherto been found only near Passau. Siliceous ore. It was discovered by Professor Hunger. It is sometimes massive, but more commonly crystallized in four-sided prisms, not longer than one fourth of an inch.

Colour reddish, yellowish, or blackish brown; sometimes whitish grey. Powder whitish grey. Lustre waxy or nearly metallic, 2 to 3. Transparency from 0 to 2. Texture foliated. Hardness 9 or more. Brittle. Sp.gr. 3.510. Muriatic acid, by repeated digestion, dissolves one-third of it. Ammonia precipitates from this solution a clammy yellowish substance. Insoluble by the blow-pipe, and also in a clay crucible; but in charcoal is converted into a black opaque porous flag.

According to the analysis of Klaproth, it is composed of:

- 33 oxyd of titanium, - 35 silica, - 33 lime.

---

(v) Dolomieu, Jour. de Min. No XLII. 231, and Sauvage, Voyage, No 1894. (x) Kirw. II. 326.—Gregor, Jour. de Phys. XXXIX. 72, and 152.—Schneider, Greffe Annals (English translation), III. 252. ORDER XX. ORES OF TELLURIUM.

Hitherto tellurium has only been found in Transylvania. It occurs in three different mines; that of Fatzbay, Offenbanya, and Nagyag, which are considered as gold mines, because they contain less or more of that metal. Its gangue is commonly quartz.

GENUS I. ALLOYS OF TELLURIUM.

SPECIES 1. White gold ore of Fatzbay.

Alloy of tellurium and iron, with some gold.

This species is generally massive. Its colour is between tin white and lead grey. Lustre considerable, metallic. Texture granular.

According to Klaproth's analysis, it is composed of:

- 72.0 iron, - 25.3 tellurium, - 2.5 gold.

100.0

SPECIES 2. Graphic golden ore of Offenbanya.

Tellurium alloyed with gold and silver.

This ore is composed of flat prismatic crystals; the arrangement of which has some resemblance to Turkish letters. Hence the name of the ore.

Colour tin white, with a tinge of brass yellow. Lustre metallic. Hardness 4 to 5. Brittle. Sp. gr. 5.725. Before the blow-pipe decrepitates, and melts like lead. Burns with a lively brown flame and disagreeable smell, and at last vanishes in a white smoke, leaving only a whitish earth.

According to Klaproth's analysis, it is composed of:

- 60 tellurium, - 30 gold, - 10 silver.

100.0

The yellow gold ore of Nagyag would belong to this species were it not that it contains lead. Its composition, according to Klaproth's analysis, is as follows:

- 45.0 tellurium, - 27.0 gold, - 19.5 lead, - 8.5 silver.

100.0 and an atom of sulphur

SPECIES 3. Grey foliated gold ore of Nagyag.

This ore is found in plates, of different degrees of thickness, adhering to one another, but easily separable; there are sometimes hexahedral, and often accumulated so as to leave cells between them.

Colour deep lead grey, passing to iron black, spotted. Lustre metallic, moderate. Texture foliated; leaves slightly flexible. Hardness 6. Sp. gr. 8.919. Stains the fingers. Soluble in acids with effervescence.

According to Klaproth, it is composed of:

- 50.0 lead, - 33.0 tellurium, - 8.5 gold, - 7.5 sulphur, - 1.0 silver and copper.

100.0

ORDER XXI. ORES OF CHROMUM.

Chromium has hitherto been found in too small quantities for its extensive application to the arts. Whenever it becomes plentiful, its properties will render it of great importance both to the dyer and painter. Nature has used it to colour some of her most beautiful mineral productions: And can art copy after a better model? Hitherto it has been found only in two places, near Ekaterinbourg in Siberia, and in the department of the Var in France. In the first of these places, and probably also in the second, its gangue is quartz.

GENUS I. SALTS OF CHROMUM.

SPECIES 1. Chromat of lead.

Red lead ore of Siberia.

This singular mineral, which has now become scarce, is found in the gold mines of Bereof near Ekaterinbourg in Siberia, crystallized in four-sided prisms, sometimes terminated by four-sided pyramids, sometimes not.

Colour red, with a shade of yellow. Lustre and powder a beautiful orange yellow. Lustre from 2 to 3. Transparency 2 to 3. Structure foliated. Texture compact. Fracture uneven. Hardness 5 to 4. Sp. gr. 6.0269 to 5.75. Does not effervesc with acids. Before the blow-pipe decrepitates; some lead is reduced, and the mineral is converted to a black slag, which tinges borax green.

According to the analysis of Vauquelin, it is composed of:

- 65.12 oxyd of lead, - 34.88 chromic acid.

100.0

SPECIES 2. Chromat of iron.

This mineral, which has been found only near Gafsin in the department of Var in France, is in irregular masses.

Colour brown, not unlike that of brown blende. Lustre metallic. Hardness moderate. Sp. gr. 4.0326. Melts with difficulty before the blow pipe; to borax it communicates a dirty green. Insoluble in nitric acid. Melted with potash, and dissolved in water, the solution assumes a beautiful orange yellow colour.

It is composed of:

- 63.6 chromic acid, - 36.0 oxyd of iron.

99.6

CHAP. IV. OF THE CHEMICAL ANALYSIS OF MINERALS.

The progress which the art of analysing minerals has made within these last twenty years is truly astonishing. To separate five or six substances intimately combined together, to exhibit each of them separately, to ascertain the precise quantity of each, and even to detect the presence and the weight of substances which do not approach tenth part of the compound, would, at no very remote period, have been considered as a hopeless, if not an impossible, task; yet this can now be done with the most rigid accuracy.

The first person who undertook the analysis of minerals was Margraff of Berlin. His attempts were in Margraff's deed rude; but their importance was soon perceived by other chemists, particularly by Bergman and Scheele, whose of whose industry and address brought the art of analysing minerals to a considerable degree of perfection.

But their methods, though they had very considerable merit, and, considering the state of the science, are wonderful proofs of the genius of the inventors, were often tedious and uncertain, and could not in all cases be applied with confidence. These defects were perceived by Mr Klaproth of Berlin, who applied himself to the analysis of minerals with a persevering industry which nothing could fatigue, and an ingenuity and accuracy which nothing could perplex. He corrected what was wrong, and supplied what was wanting, in the analytical method; invented new processes, discovered new instruments; and it is to his labours, more than to those of any other chemist, that the degree of perfection, to which the analysis of minerals has attained, is to be ascribed. Many improvements, however, were introduced by other chemists, especially by Mr Vauquelin, whose analyses in point of accuracy and ingenuity rival those of Klaproth himself.

We shall, in this chapter, give a short description of the most perfect method of analysing minerals, as far as we are acquainted with it. We shall divide the chapter into four sections. In the first, we shall give an account of the instruments used in analyses; in the second, we shall treat of the method of analysing stones; in the third, of analysing combustibles; and in the fourth, of the analyses of ores.

**Sect. I. Of the Instruments of Analysis.**

1. The chemical agents, by means of which the analysis of minerals is accomplished, ought to be prepared with the greatest care, because upon their purity the exactness of the operation entirely depends. These agents are the three alkalies, both pure and combined with carbonic acid; the sulphuric, nitric, and muriatic acids; hydrofluosilicet of potash and sulphurated hydrogen gas dissolved in water; prussic alkali, and a few neutral salts.

2. Potash and soda may be obtained pure, either by means of alcohol, or by the method described in the article Chemistry, n° 372. Suppl. These alkalies are known to be pure when their solution in pure water occasions no precipitate in lime and barytic water; when the precipitate which it produces in a solution of silver is completely dissolved by nitric acid; and, lastly, when saturated with carbonic acid it deposits no silica.

3. The carbonates of potash and soda may be formed by dissolving the potash and soda of commerce in pure water, saturating the solution with carbonic acid, and crystallizing them repeatedly. When pure, these crystals effloresce in the air; and the precipitate which they occasion in solutions of barytes and of silver is completely soluble in nitric acid. Carbonate of ammonia is obtained by distilling together one part of muriat of ammonia and two parts of carbonate of lime.

4. The sulphuric acid of commerce often contains nitric acid, potash, lead, &c. It may be purified by distillation in a low cucurbite. The first portion, when it comes over, must be set aside; it contains the nitric acid of the mineral. The other impurities remain behind in the cucurbite. Sulphuric acid, when pure, dissolves indigo without altering its colour, does not attack mercury while cold, and causes no precipitate in pure alkaline solutions.

5. Nitric acid often contains both sulphuric and muriatic acids. It is easily purified by throwing into it about three parts of litharge in fine powder for every 100 parts of the acid, allowing the mixture to remain for 24 hours, shaking it occasionally; and then distilling it. The sulphuric and muriatic acids combine with the lead, and remain behind in the retort. Pure nitric acid occasions no precipitate in the solutions of barytes and silver.

6. The muriatic acid of commerce usually contains sulphuric acid, oxymuriatic acid, and oxyd of iron. It may be purified by distillation with a little muriat of soda; taking care to set aside the first portion which comes over. When pure it causes no precipitate in the solution of barytes, nor of pure alkalies, and does not attack mercury while cold.

7. Hydrofulphuret of potash is made by saturating a solution of pure potash with sulphurated hydrogen gas; and water may be saturated with sulphurated hydrogen gas in the same manner. See Chemistry, n° 857. Suppl.

8. The method of preparing prussic alkali, oxalic acid, and the other substances used in analyses, has been already described in the article Chemistry, Suppl. It is unnecessary therefore to repeat it here.

II. Before a mineral is submitted to analysis, it ought to be reduced to an impalpable powder. This is by no means an easy task when the stone is extremely hard mineral. It ought to be raised to a bright red or white heat in a crucible, and then instantly thrown into cold water. This sudden transition makes it crack and break into pieces. If these pieces are not small enough, the operation may be repeated on each till they are reduced to the proper size. These fragments are then to be beaten to small pieces in a polished steel mortar; the cavity of which should be cylindrical, and the steel pestle should fit it exactly, in order to prevent any of the stone from escaping during the act of pounding. As soon as the stone is reduced to pretty small pieces, it ought to be put into a mortar of rock crystal or flint, and reduced to a coarse powder. This mortar should be about four inches in diameter, and rather more than an inch in depth. The pestle should be formed of the same stone with the mortar, and care should be taken to know exactly the ingredients of which this mortar is composed. Klaproth's mortar is of flint. We have given its analysis in n° 321 of this article.

When the stone has been reduced to a coarse powder, a certain quantity, whose weight is known exactly, 100 grains for instance, ought to be taken and reduced to as fine a powder as possible. This is best done by pounding small quantities of it at once, not exceeding 10 grams. The powder is as fine as possible when it feels soft, adheres together, and as it were forms a cake under the pestle. It ought then to be weighed exactly. It will almost always be found heavier after being pounded than it was before; owing to a certain quantity of the substance of the mortar which has been rubbed off during the grinding and mixed with the powder. This additional weight must be carefully noted; and after the analysis, a portion of the ingredients of the mortar, corresponding to it, must be subtracted.

III. It is necessary to have a crucible of pure silver, or, what is far preferable, of platinum, capable of holding rather more than seven cubic inches of water, and provided with a cover of the same metal. There should also be ready a spatula of the same metal about four inches long.

The dishes in which the solutions, evaporations, &c., are performed, ought to be of glass or porcelain. Those of porcelain are cheaper, because they are not so apt to break. Those which Mr Vanquelin uses are of porcelain; they are sections of spheres, and are glazed both within and without, except that part of the bottom which is immediately exposed to the fire.

Sect. II. Analysis of Stones (v).

The only substances which enter into the composition of the simple stones, as far at least as analysis has discovered, are the six earths, silica, alumina, zirconia, glaucia, lime, and magnesia; and the oxyds of iron, manganese, nickel, chromium, and copper (z). Seldom more than four or five of these substances are found combined together in the same stone: we shall suppose, however, in order to prevent unnecessary repetitions, that they are all contained in the mineral which we are going to analyze.

Let 100 or 200 grains of the stone to be analyzed, previously reduced to a fine powder, be mixed with three times its weight of pure potash and a little water, and exposed in the silver or platinum crucible to a strong heat. The heat should at first be applied slowly, and the matter should be constantly stirred, to prevent the potash from swelling and throwing any part out of the crucible. When the whole water is evaporated, the mixture should be kept for half an hour or three quarters in a strong red heat.

If the matter in the crucible melts completely, and appears as liquid as water, we may be certain that the stone which we are analyzing consists chiefly of silica; if it remains opaque, and of the consistence of patte, the other earths are most abundant; if it remains in the form of a powder, alumina is the prevalent earth. If the matter in the crucible be of a dark or brownish red colour, it contains oxyd of iron; if it is green, manganese is present; if it is yellowish green, it contains chromium.

When the crucible has been taken from the fire and wiped on the outside, it is to be placed in a capsule of porcelain, and filled with water. This water is to be renewed from time to time till all the matter is detached from the crucible. The water dissolves a part of the combination of the alkali with the silica and alumina of the stone, and if a sufficient quantity were used, it would dissolve the whole of that combination.

Muriatic acid is now to be poured in till the whole of the matter is dissolved. At first a flaky precipitate appears; because the acid combines with the alkali which kept it in solution. Then an effervescence takes place, owing to the decomposition of some carbonat of potash formed during the fusion. At the same time the flaky precipitate is redissolved; as is also that part of the matter which, not having been dissolved in the water, had remained at the bottom of the dish, in the form of a powder. This powder, if it consists only of silica and alumina, dissolves without effervescence; but if it contains lime, an effervescence takes place.

If this solution in muriatic acid be colourless, we may conclude that it contains no metallic oxyd, or only a very small portion; if its colour be purplish red, it contains manganese; orange red indicates the presence of iron; and golden yellow the presence of chromium.

This solution is to be poured into a capsule of porcelain, covered with paper, and evaporated to dryness in a sand bath. When the evaporation is drawing towards its completion, the liquor assumes the form of jelly. It must then be stirred constantly with a glass or porcelain rod, in order to facilitate the disengagement of the acid and water, and to prevent one part of the matter from being too much, and another not sufficiently dried. Without this precaution, the silica and alumina would not be completely separated from each other.

When the matter is reduced almost to a dry powder, a large quantity of pure water is to be poured on it; it fuses, and, after exposure to a flight heat, the whole is to be passed, poured on a filter. The powder which remains upon the filter is to be washed repeatedly, till the water with which it has been washed ceases to precipitate silica from its solutions. This powder is the whole of the silica which the stone that we are analyzing contained. It must first be dried between folds of blotting paper, then heated red hot in a platinum or silver crucible, and weighed while it is yet warm. It ought to be a fine powder, of a white colour, not adhering to the fingers, and entirely soluble in acids. If it be coloured, it is contaminated with some metallic oxyd; and flows, that the evaporation to dryness has been performed at too high a temperature. To separate this oxyd, the silica must be boiled with an acid, and then washed and dried as before. The acid solution must be added to the water which passed through the filter, and which we shall denominate A.

The watery solution A is to be evaporated till its quantity does not exceed 30 cubic inches, or nearly an English pint. A solution of carbonat of potash is then to be poured into it till no more matter precipitates. It ought to be boiled a few moments to enable all the precipitate to fall to the bottom. When the whole of the precipitate has collected at the bottom, the supernatant liquid is to be decanted off; and water being substituted in its place, the precipitate and water are to be thrown upon a filter. When the water has run off, the filter with the precipitate upon it is to be placed between folds of blotting paper. When the precipitate has acquired some consistence, it is to be carefully collected by an ivory knife, mixed with a solution of pure potash, and boiled in a porcelain capsule. If any

(v) Part of this section is to be considered as an abstract of a treatise of Vanquelin on the analysis of stones, published in the Annales de Chimie, Vol. XXX. p. 66.

(z) Barytes has also been discovered in one single stone, the fluorite; but its presence in stones is so uncommon, that it can scarcely be looked for. The method of detecting it shall be noticed afterwards. alumina or glaucia be present, they will be dissolved in the potas; while the other substances remain untouched in the form of a powder, which we shall call B.

Into the solution of potas as much acid must be poured as will not only saturate the potas, but also completely redissolve any precipitate which may have at first appeared. Carbonat of ammonia is now to be added in such quantity that the liquid shall taste of it. By this addition the whole of the alumina will be precipitated in white flecks, and the glaucia will remain dissolved, provided the quantity of carbonat of ammonia used be not too small. The liquid is now to be filtered, and the alumina which will remain on the filter is to be washed, dried, heated red hot, and then weighed. To see if it be really alumina, dissolve it in sulphuric acid, and add a sufficient quantity of sulphat or acetate of potas; if it be alumina, the whole of it will be converted into crystals of alum.

Let the liquid which has passed through the filter be boiled for some time, and the glaucia, if it contains any, will be precipitated in a light powder, which may be dried and weighed. When pure, it is a fine, soft, very light, talc-like powder, which does not concretize when heated, as alumina does.

The residuum B may contain lime, magnesia, and one or more metallic oxys. Let it be dissolved in weak sulphuric acid, and the solution evaporated to dryness. Pour a small quantity of water on it. The water will dissolve the sulphat of magnesia, and the metallic sulphats; but the sulphat of lime will remain undissolved. Let it be heated red hot in a crucible, and weighed. The lime amounts to 0.41 of the weight.

Let the solution containing the remaining sulphats be diluted with a large quantity of water, let a small excess of acid be added, and then let a saturated carburet of potas be poured in. The oxys of chromium, iron, and nickel, will be precipitated, and the magnesia and oxyd of manganese will remain dissolved. The precipitate we shall call C.

Into the solution let a solution of hydrofulphurat of potas be poured, and the manganese will be precipitated in the state of a hydrofulphurat. Let it be calcined in contact with air, and weighed. The magnesia may then be precipitated by pure potas, washed, exposed to a red heat, and then weighed.

Let the residuum C be boiled repeatedly with nitric acid, then mixed with pure potas; and after being heated, let the liquid be decanted off. Let the precipitate, which consists of the oxys of iron and nickel, be washed with pure water; and let this water be added to the solution of the nitric acid and potas. That solution contains the chromium converted into an acid. Add to this solution an excess of muriatic acid, and evaporate till the liquid assumes a green colour; then add a pure alkali: The chromium precipitates in the state of an oxyd, and may be dried, and weighed.

Let the precipitate, consisting of the oxys of iron and nickel, be dissolved in muriatic acid; add an excess of ammonia: the oxyd of iron precipitates. Let it be washed, dried, and weighed.

Evaporate the solution, and the oxyd of nickel will also precipitate; and its weight may be ascertained in the same manner with the other ingredients.

The weights of all the ingredients obtained are now to be added together, and their sum total compared with the weight of the matter submitted to analysis. If the analysis of two are equal, or if they differ only by .03 or .04 parts, we may conclude that the analysis has been properly performed; but if the loss of weight be considerable, something or other has been lost. The analysis must therefore be repeated with all possible care. If there is still the same loss of weight, we may conclude that the stone contains some substance, which has either evaporated by the heat, or is soluble in water.

A fresh portion of the stone must therefore be broken into small pieces, and exposed in a porcelain crucible to a strong heat. If it contains water, or any volatile body, the volatile substance will come over into the receiver; and their nature and weight may be ascertained.

If nothing comes over into the receiver, or if what comes over is not equal to the weight wanting, we may conclude that the stone contains some ingredient which is soluble in water.

To discover whether it contains potas, let the stone, Method of reduced to an impalpable powder, be boiled five or six times in succession, with very strong sulphuric acid, applying a pretty strong heat towards the end of the operation, in order to expel the excess of acid; but taking care that it be not strong enough to decompose the salts which have been formed.

Water is now to be poured on, and the residuum, which does not dissolve, is to be washed with water till it becomes talc-like. The watery solution is to be filtered, and evaporated to dryness, in order to drive off any excess of acid which may be present. The salts are to be again dissolved in water; and the solution, after being boiled for a few moments, is to be filtered and evaporated to a consistence proper for crystallizing. If the stone contains a sufficient quantity of alumina, and it potas be present, crystals of alum will be formed; and the quantity of potas may be discovered by weighing them, it being nearly 1/5th of their weight. If the stone does not contain alumina, or not in sufficient quantity, a solution of pure alumina in sulphuric acid must be added. Sometimes the alum, even when potas is present, does not appear for several days, or even weeks; and sometimes, when a great quantity of alumina is present, if the solution has been too much concentrated by evaporation, the sulphat of alumina prevents the alum from crystallizing at all. Care, therefore, must be taken to prevent this last source of error. The alum obtained may be dissolved in water, and barytic water poured into it as long as any precipitate forms. The liquor is to be filtered, and evaporated to dryness. The residuum will consist of potas and a little carbonat of potas. The potas may be dissolved in a little water. This solution, evaporated to dryness, gives us the potas pure; which may be examined and weighed.

If no crystals of alum can be obtained, we must look for some other substance than potas. The stone, for instance, may contain soda. The presence of this alkali may be discovered by decomposing the solution in sulphuric acid, already described, by means of ammonia. The liquid which remains is to be evaporated to dryness, and the residuum is to be calcined in a crucible. By this method, the sulphat of ammonia will be volatilized, and the soda will remain. It may be redissolved in water, crystallized, and examined.

If sulphuric acid does not attack the stone, as is often the case, it must be decomposed by fusion with fo- Analysis of minerals.

The matter, after fusion, is to be diluted with water, and then saturated with sulphuric acid. The solution is to be evaporated to dryness; the residuum again dissolved in water, and evaporated. Sulphat of soda will crystallize first; and by a second evaporation, if the stone contains potash and alumina, crystals of alum will be deposited.

The presence of potash may be discovered, by mixing with a somewhat concentrated solution of muriatic acid of platinum, the salt obtained, either by decomposing the stone immediately by an acid, or by saturating with an acid the matter obtained by fusing the stone with soda. If any potash be present, a very red precipitate will be formed. This precipitate is a triple salt, composed of potash, muriatic acid, and oxyd of platinum. Ammonia, indeed, produces the same precipitate; but ammonia has not hitherto been discovered in stones.

In this manner may simple stones and aggregates be analyzed. As to saline stones, their analysis must vary according to the acid which they contain. But almost all of them may be decomposed by one or other of two methods; of each of which we shall give an example.

I. Analysis of Carbonat of Strontites.

Klaproth analyzed this mineral by dissolving 100 parts of it in diluted muriatic acid; during the solution, 30 parts of carbonic acid escaped. The solution crystallized in needles, and when dissolved in alcohol, burnt with a purple flame. Therefore it contained strontites. He dissolved a grain of sulphat of potash in six ounces of water, and let fall into it three drops of the muriatic solution. No precipitate appeared till next day. Therefore the solution contained no barytes; for if it had, a precipitate would have appeared immediately.

He then decomposed the muriatic acid solution, by mixing it with carbonat of potash. Carbonat of strontites precipitated. By the application of a strong heat, the carbonic acid was driven off. The whole of the earth which remained was dissolved in water. It crystallized; and when dried, weighed 69½.

II. Analysis of Sulphat of Strontites.

Mr Vauquelin analyzed an impure specimen of this mineral as follows:

On 200 parts of the mineral, diluted nitric acid was poured. A violent effervescence took place, and part of the mineral was dissolved. The undissolved portion, after being heated red hot, weighed 167. Therefore 33 parts were dissolved.

The nitric solution was evaporated to dryness: A reddish substance remained, which indicated the presence of oxyd of iron. This substance was redissolved in water, and some ammonia mixed with it; a reddish precipitate appeared, which, when dried, weighed 1, and was oxyd of iron. The remainder of the solution was precipitated by carbonat of potash. The precipitate weighed, when dried, 20, and possessed the properties of carbonat of lime. Therefore 200 parts of this mineral contain 20 of carbonat of lime, 1 of oxyd of iron, and the remainder of the 33 parts he concluded to be water.

The 167 parts, which were insoluble in nitric acid, were mixed with 500 parts of carbonat of potash, and 7000 parts of water, and boiled for a considerable time. The solution was then filtered, and the residuum washed. The liquid scarcely effervesced with acids; but with barytes it produced a copious precipitate, totally indissoluble in muriatic acid. Therefore it contained sulphuric acid.

The undissolved residuum, when dried, weighed 129 parts. It dissolved completely in muriatic acid. The solution crystallized in needles; when dissolved in alcohol, it burnt with a purple flame; and, in short, had all the properties of muriat of strontites. Therefore these 129 parts were carbonat of strontites. Now, 100 parts of this carbonat contain 30 of carbonic acid; therefore 129 contain 38.7. Therefore the mineral must contain in 200 parts 90.3 of strontites.

Now, the insoluble residuum of 167 parts was pure sulphat of strontites; and we have seen that it contained 90.3 of strontites. Therefore the sulphuric acid must amount to 76.7 parts.

Nearly in the same manner as in the first of these examples, may the analysis of carbonat of lime and barytes be performed; and nearly in the same manner with the second, we may analyze the sulphats of lime and barytes.

Phosphat of lime may be dissolved in muriatic acid, and the lime precipitated by sulphuric acid, and its quantity ascertained by decomposing the sulphat of lime obtained. The liquid solution may be evaporated to the consistence of honey, mixed with charcoal powder, and distilled in a strong heat. By this means phosphorus will be obtained. The impurities with which the phosphat may be contaminated will partly remain undissolved, and be partly dissolved, in muriatic acid. They may be detected and ascertained by the rules laid down in the second section of this chapter.

The float of lime may be mixed with sulphuric acid and distilled. The fluoric acid will come over in the form of gas, and its weight may be ascertained. What remains in the retort, which will consist chiefly of sulphat of lime, may be analyzed by the rules already laid down.

The borat of lime may be dissolved in nitric or fulminic acid: The solution may be evaporated to dryness, and the boracic acid separated from the residuum by means of alcohol, which will dissolve it without acting on any of the other ingredients. The remainder of the dry mass may be analyzed by the rules laid down in Sect. II. of this Chapter.

Sect. III. Of the Analysis of Combustibles.

The only combustibles of whose analysis it will be necessary to speak are coals and sulphur; for the method of analyzing the diamond and oil has already been given in the article Chemistry, Suppl.

Coal is composed of carbon, bitumen, and some portion of earth. The earths may be detected by burning coal he completely a portion of the coal to be analyzed. The ashes which remain after incineration consist of the earthy part. Their nature may be ascertained by the rules laid down in Sect. II. of this Chapter.

For the method of ascertaining the proportion of carbon and bitumen in coal, we are indebted to Mr Kirwan.

When nitre is heated red hot, and charcoal is thrown on it, a violent detonation takes place; and if the quantity of charcoal be sufficient, the nitre is completely decomposed. Now, it requires a certain quantity of pure and bituminous carbon. The experiments of Lavoisier, it follows, that when the detonation is performed in close vessels under water, 13.34 parts of charcoal are capable of decomposing 100 parts of nitre*. But when the detonation is performed in an open crucible, a smaller proportion of charcoal is necessary, because part of the nitre is decomposed by the action of the surrounding air. Scheele found, that under these circumstances 10 parts of plumbago were sufficient to decompose 96 parts of nitre, and Mr Kirwan found, that nearly the same quantity of charcoal was sufficient for producing the same effect.

Macquer long ago observed, that no volatile oily matter will detonate with nitre, unless it be previously reduced to a charcoal; and that then its effect upon nitre is precisely proportional to the charcoal which it contains†. Mr Kirwan, upon trying the experiment with vegetable pitch and maltha, found, that these substances did not detonate with nitre, but merely burn upon its surface with a white or yellow flame; and that after they were consumed, nearly the same quantity of charcoal was necessary to decompose the nitre which would have been required if no bitumen had been used at all‡.

Now coals are chiefly composed of charcoal and bitumen. It occurred therefore to Mr Kirwan, that the quantity of charcoal which any coal contains may be ascertained by detonating it with nitre: For since the bitumen of the coal has no effect in decomposing nitre, it is evident that the detonation and decomposition must be owing to the charcoal of the coal; and that therefore the quantity of coal necessary to decompose a given portion of nitre will indicate the quantity of carbon which it contains: and the proportion of charcoal and earth which any coal contains being ascertained, its bituminous part may be easily had from calculation.

The crucible which he used in his experiments was large; it was placed in a wind furnace at a distance from the flue, and the heat in every experiment was as equal as possible. The moment the nitre was red hot, the coal, previously reduced to small pieces of the size of a pin head, was projected in portions of one or two grains at a time, till the nitre would no longer detonate; and every experiment was repeated several times to ensure accuracy.

He found, that 480 grains of nitre required 50 grains of Kilkenny coal to decompose it by this method. Therefore 10 grains would have decomposed 96 of nitre; precisely the quantity of charcoal which would have produced the same effect. Therefore Kilkenny coal is composed almost entirely of charcoal.

Cannel coal, when incinerated, left a residuum of 3.12 in the 100 parts of earthy ashes. 66.5 grains of it were required to decompose 480 grains of nitre; but 50 parts of charcoal would have been sufficient: therefore 66.5 grains of cannel coal contain 50 grains of charcoal, and 2.08 of earth; the remaining 14.42 grains must be bitumen. In this manner may the composition of any other coal be ascertained.

As for sulphur, in order to ascertain any accidental impurities with which it may be contaminated, it ought to be boiled in thirty times its weight of water, afterwards in diluted muriatic acid, and lastly in diluted nitro-muriatic acid. These substances will deprive it of all its impurities without acting on the sulphur itself, at least if the proper cautions be attended to. The

Sect. IV. Of the Analysis of Ores.

The method of analysing ores must vary considerably, according to the metals which they are suspected of containing. A general method, therefore, of analysing ores, would be of no use, even if it could be given, because it would be too complicated ever to be practised. We shall content ourselves with exhibiting a sufficient number of the analyses of ores, to take in most of the cases which can occur. He who wishes for more information on the subject, may consult the treatise of Bergman on the Analysis of Ores; Mr Kirwan's treatise on the same subject; and, above all, he ought to study the numerous analyses of ores which have been published by Mr Klaproth.

I. Analysis of Red Silver Ore.

Mr Vauquelin analysed this ore as follows:

He reduced 100 parts of it to fine powder, poured a solution over it, 500 parts of nitric acid previously diluted with red silver water, and applied a gentle heat to the mixture. The colour of the powder, which before the mixture with nitric acid was a deep purple, became gradually lighter, till at last it was pure white. During this change no nitrous gas was extricated; hence he concluded, that the metals in the ore were in the state of oxyds.

When the nitric acid, even though boiled gently, did not appear to be capable of dissolving any more of the powder, it was decanted off, and the residuum, after being carefully washed, weighed 42.66.

Upon these 42.66 parts concentrated muriatic acid was poured; and by the application of heat, a considerable portion was dissolved. The residuum was repeatedly washed with muriatic acid, and then dried. Its weight was 14.6666. One portion of these 14.6666 parts, when thrown upon burning coals, burnt with a blue flame and sulphureous fumes. Another portion sublimed in a close vessel without leaving any residuum. In short, they had all the properties of sulphur. Therefore 100 parts of red silver ore contain 14.6666 of sulphur.

The muriatic acid solution was now diluted with a great quantity of water; it became milky, and deposited a white flaky powder, which when washed and dried weighed 21.25. This powder, when heated with tartar in a crucible, was converted into a bluish white brittle metal, of a foliated texture, and possessing all the other properties of antimony. Red silver ore therefore contains 21.25 of oxyd of antimony.

The solution in nitric acid remained now to be examined. When muriatic acid was poured into it, a copious white precipitate appeared, which, when washed and dried, weighed 72.66. It had all the properties of muriat of silver. According to Mr Kirwan's tables, 72.66 of muriat of silver contain 60.57 of oxyd of silver. Therefore red silver ore, according to this analysis, is composed of

- 60.57 oxyd of silver, - 21.25 oxyd of antimony, - 14.66 sulphur.

96.48 Analysis of The lofs, which amounts to 3.52 parts, is to be averted to unavoidable errors which attend such experiments.

II. Antimoniated Silver Ore.

Klaproth analysed this ore as follows:

On 100 parts of the ore, reduced to a fine powder, he poured diluted nitric acid, raised the mixture to a boiling heat, and after pouring off the acid, added new quantities repeatedly, till it would dissolve nothing more. The residuum was of a greyish yellow colour, and weighed, when dry, 26.

These 26 parts he digested in a mixture of nitric and muriatic acid; part was dissolved, and part still remained in the form of a powder. This residuum, when washed and dried, weighed 13 parts. It had the properties of sulphur; and when burnt, left a residuum of one part, which had the properties of silica. Antimoniated silver ore, therefore, contains, in the 100 parts, 12 parts of sulphur and 1 of silica.

When the nitro-muriatic solution was diluted with about 20 times its weight of water, a white precipitate appeared; which, when heated to redness, became yellow. Its weight was 13. No part evaporated at a red heat; therefore it contained no arsenic. On burning coals, especially when soda was added, part was reduced to a metal, having the properties of antimony; and in a pretty high heat, the whole evaporated in a grey smoke. These 13 parts were therefore oxyd of antimony: They contain about 10 parts of metallic antimony; and as the state of oxyd was produced by the action of the nitric acid, we may conclude, that antimoniated silver ore contains 10 parts of antimony.

The nitric acid solution remained still to be examined. It was of a green colour. When a solution of common salt was poured in, a white precipitate was obtained, which possessed the properties of muriat of silver. When dried, it weighed 87.75 parts; and when reduced, 65.81 parts of pure silver were obtained from it. Antimoniated silver ore, therefore, contains 65.81 of silver.

Into the nitric acid solution, thus deprived of the silver, he dropped a little of the solution of sulphat of soda; but no precipitate appeared. Therefore it contained no lead.

He superaturated it with pure ammonia, on which a grey precipitate appeared. When dried, it weighed 5 parts. This, on burning coals, gave out an arsenical smell. It was redissolved in nitric acid; sulphurated alkali occasioned a smutty brown precipitate; and prussic alkali a prussian blue, which, after torrefaction, was magnetic. Hence he concluded, that these 5 parts were a combination of iron and arsenic acid.

The nitric solution, which had been superaturated with ammonia, was blue; he therefore suspected that it contained copper. To discover this, he saturated it with sulphuric acid, and put into it a polished plate of iron. The quantity of copper was so small, that none could be collected on the iron.

III. Grey Copper Ore.

Klaproth analysed this ore as follows:

Three hundred grains of it, not completely freed from its matrix, were reduced to a fine powder; four times their weight of nitric acid was poured on them, and the whole was digested. The acid was then poured off, and an equal quantity again digested on the residuum. The two acid solutions were mixed together. The residuum was of a yellowish grey colour, and weighed 188 grains.

On this residuum five times its weight of muriatic acid was boiled. The residuum was washed, first with muriatic acid, and afterwards with alcohol, and the washings added to the muriatic acid solution. The residuum, when dried, weighed 195.4 grams. Part of it burned with a blue flame; and was therefore sulphur. The residuum amounted to 80.25 grams, and had the properties of silica. When melted with black flux, about ¼ths of a grain of silver were obtained from it. Thus 300 parts of grey copper ore contain 25.25 grs. of sulphur, and 79.75 of silica.

The muriatic acid solution, which was of a light yellow colour, was concentrated by distillation, a few crystals of muriat of silver appeared in it, which contained about ¼th grain of silver. The solution, thus concentrated, was diluted with a great quantity of water; a white precipitate was deposited, which, when dried, weighed 97.25 grams. It possessed the properties of oxyd of antimony, and contained 75 grams of antimony. Therefore 300 grams of grey copper ore contain 70 of antimony.

The nitric acid solution was of a clear green colour. A solution of common salt occasioned a white precipitate, which was muriat of silver, and from which 31.5 grams of silver were obtained.

A little sulphat of potash, and afterwards sulphuric acid, were added, to see whether the solution contained lead; but no precipitate appeared.

The solution was then superaturated with ammonia; a loose fleaky brownish red precipitate appeared, which, when heated to redness, became brownish black, and weighed 9½th grams. This precipitate was dissolved in muriatic acid; half a grain of matter remained undissolved, which was silica. The muriatic acid solution, when prussic alkali was added, afforded a blue precipitate; and soda afterwards precipitated 1.5 grams of alumina. Therefore 300 grams of grey copper ore contain 7.25 grams of iron, and 1.5 of alumina.

Into the nitric solution superaturated with ammonia, and which was of an azure blue colour, a polished plate of iron was put: By this method 69 grams of copper were obtained.

IV. Sulphuret of Tin.

Klaproth analysed this ore as follows:

On 120 grams of the ore reduced to powder, six times their weight of nitro muriatic acid, composed of 1.48 parts of muriatic, and 1 of nitric acid, were poured. There remained undissolved 43 grams, which had the appearance of sulphur; but containing green spots, was suspected not to be pure. After a gentle combustion, 13 grams remained; 8 of which were dissolved in nitro-muriatic acid, and added to the first solution. The remaining 5 were separated by the filter, and heated along with wax. By this method about a grain of matter was obtained, which was attracted by the magnet; and which therefore was iron. The residuum weighed 3 grams, and was a mixture of alumina and silica. Thus 120 grams of sulphuret of tin contain 30 grams of sulphur, 1 of iron, and 3 of alumina and silica. The nitro-muriatic solution was completely precipitated by potash. The precipitate was of a greyish green colour. It was washed and dried, and again dissolved in diluted muriatic acid. Into the solution a cylinder of pure tin was put, which weighed exactly 217 grains. The solution became gradually colourless, and a quantity of copper precipitated on the cylinder of tin, which weighed 44 grains. To see whether it was pure, a quantity of nitric acid was digested on it; the whole was dissolved, except one grain of tin. Therefore 120 grains of sulphuret of tin contains 43 grains of copper.

The cylinder of tin now weighed only 128 grains; so that 89 grains had been dissolved. Into the solution a cylinder of zinc was put; upon which a quantity of tin precipitated. When washed and dried, it weighed 130 grains. The tin he melted with tallow and powdered charcoal; and when cold, he washed off the charcoal. Among the tin globules were found some black flocculi of iron, which weighed one grain. Deducting this grain, and the 89 grains of the tin cylinder which had been dissolved, we see that the 120 grains of sulphuret of tin contained 40 grains of tin besides the grain which had been detected in the copper.

V. Plumbiferous Antimonished Silver Ore.

Klaproth analysed this ore as follows:

He digested 400 grains of it, reduced to a fine powder, first in five times its weight of nitric acid, and then in twice its weight of the same acid. He then diluted this last portion of acid with eight times its weight of water, and continued the digestion. The undissolved residuum, when washed and dried, weighed 326 grains.

On this residuum he boiled muriatic acid repeatedly. The solution, on cooling, deposited acicular crystals. These he carefully separated, and put by. The undissolved residuum weighed 51 grains. It had the properties of sulphur. When burned, it left one grain of silica.

The muriatic acid solution was concentrated to half its former bulk by distillation; this made it deposit more acicular crystals. He continued the distillation as long as any crystals continued to appear. He then collected the whole of these crystals together. They had the properties of muriate of lead. When mixed with twice their weight of black flux, and heated in a crucible lined with charcoal, they yielded 160½ grains of lead.

Sulphuret of ammonia was now added to the muriatic acid solution; an orange-coloured precipitate appeared, which showed that the solution contained antimony. It was precipitated by a copious effusion of water, and by soda. The oxyd of antimony being reduced to a mass with Spanish soap, mixed with black flux, and heated in a lined crucible, yielded 28.5 grains of antimony.

Into the nitric acid solution, obtained by the first part of the process, a solution of muriate of soda was dropped; a white precipitate was deposited, and over it acicular crystals. These crystals he dissolved, by pouring boiling water on the precipitate. The water was added to the nitric acid solution. The white precipitate was muriate of silver; when heated with twice its weight of soda, it yielded 81.5 grains of silver.

He now concentrated the nitric acid solution by evaporation; and then adding a solution of sulphate of soda, a white precipitate was obtained, which had the properties of sulphate of lead, and weighed 43 grains. It contained 32 grains of pure lead.

He now poured ammonia into the solution; a pale brown precipitate was obtained, which weighed 40 grains, and which appeared to consist of oxyd of iron and alumina. He redissolved it in nitric acid, precipitated the iron by prussic alkali, and the alumina by soda. The alumina, after being heated to redness, weighed 28 grains; consequently the oxyd of iron was 12 grains, which is equivalent to 9 grains of iron.

VI. Molybdate of Lead.

Mr Hatchett analysed this ore as follows:

On 250 grains of the ore, reduced to a fine powder, he poured an ounce of strong sulphuric acid, and digested the mixture in a strong heat for an hour. When molybdate of lead was cool, and had settled, he decanted it off, and washed the undissolved powder with pure water, till it came away tailleless. This operation was repeated twice more; so that three ounces of sulphuric acid were used. All these solutions were mixed together, and filtered.

Four ounces of a solution of carbonat of soda were poured upon the powder which remained undissolved, and which consisted of sulphate of lead. The mixture was boiled for an hour, and then poured off. The powder was then washed, and diluted nitric acid poured on it: The whole was dissolved, except a little white powder, which, when washed, and dried on a filter by the heat of boiling water, weighed seven-tenths of a grain. It possessed the properties of silica.

The nitric acid solution was saturated with pure soda; a white precipitate was obtained, which, when washed, and dried for an hour in a heat rather below redness, weighed 146 grams. It possessed the properties of oxyd of lead.

To see whether this oxyd of lead contained any iron, it was dissolved in diluted nitric acid, and the lead precipitated by sulphuric acid. The solution was then saturated with ammonia; a brown powder precipitated, which, when dried, weighed one grain, and had the properties of oxyd of iron.

The sulphuric acid solution was of a pale blue colour; it was diluted with 1.6 times its weight of pure water, and then saturated with ammonia. It became of a deep blue colour, and appeared turbid. In 24 hours a pale yellow precipitate subsided, which, when collected on a filter, and dried by a boiling water heat, weighed 4.2 grams. Its colour was yellowish brown. Muriatic acid dissolved it, and prussic of potash precipitated it from its solution in the state of prussian blue. It was therefore oxyd of iron.

The sulphuric acid solution, saturated with ammonia, was gradually evaporated to a dry salt. This salt was a mixture of molybdate of ammonia and sulphate of ammonia. A strong heat was applied, and the distillation continued till the whole of the sulphate of ammonia was driven off; and to be certain that this was the case, the fire was raised till the retort became red hot. The residuum in the retort was a black blistered mass; three ounces of nitric acid, diluted with water, were poured upon it, and distilled off. The operation was again repeated. Analysis of peated. By this method the oxyd of molybdenum was converted into a yellow powder, which was yellow acid of molybdenum. It weighed 95 grains.

VII. Grey Ore of Manganese.

Mr. Vauquelin analysed this ore as follows:

When 200 grains of it were exposed to a strong heat in a retort, there came over 10 grains of water, and 18 grey ore of cubic inches of oxygen gas, mixed with a little carbonic acid gas. The mineral now weighed only 176 grains. Therefore the weight of the gas was 14 grains.

On 200 grains of the same mineral muriatic acid was poured, and heat applied. 75 cubic inches of oxy muriatic acid gas came over, which, though mixed with some carbonic acid gas, enlarged metals when reduced to powder. When no more gas came over, the residuum was boiled. The whole was dissolved, except a white powder, which weighed 12 grains, and which possessed the properties of silica.

Carbonat of potas was poured into the solution; a white precipitate was obtained, which became black by exposure to the air, and weighed 288 grains. Strong nitric acid was boiled on it repeatedly to dryness. It became of a deep black colour, and, when well washed with water and dried, weighed 164 grains. This powder was black oxyd of manganese.

To see whether it contained iron, nitric acid, with a little sugar, was poured upon it, and digested on it. The acid dissolved it completely. Therefore no oxyd of iron was present.

Into the water with which the black oxyd of manganese had been washed, carbonat of potas was poured; a white powder precipitated, which, when dried, weighed 149 grains, and which possessed the properties of carbonat of lime.

VIII. Wolfram.

Messrs Vauquelin and Hecht analysed this mineral as follows:

On 200 parts of Wolfram in powder, three times its weight of muriatic acid were poured, and the mixture boiled for a quarter of an hour; a yellow powder appeared, and the solution was of a brown colour. The acid was allowed to cool, and then carefully decanted off, and the residuum washed. The residuum was then digested for some hours with ammonia, which dissolved a part of it. The residuum was washed, and new muriatic acid again poured over it; then the residuum was digested with ammonia, as before; and the operation was continued till the whole wolfram was dissolved.

All the ammoniacal solutions being joined together, were evaporated to dryness, and the salt which remained was calcined: a yellow powder was obtained; it weighed 134 grains, and was yellow acid of tungsten.

Into the muriatic acid solutions, which were all mixed together, a sufficient quantity of sulphuric acid was poured to decompose all the salts. The solution was then evaporated to dryness; and the salts which were obtained by this evaporation were redissolved in water.

A white powder remained, which weighed three grains, and which possessed the properties of silica.

The excess of acid of the solution was saturated with carbonat of potas; the liquor became brown, but nothing precipitated. When boiled, a red powder precipitated, and the brown colour disappeared. The addition of more carbonat of potas caused a farther precipitation of a yellowish powder. This precipitate consisted of the oxyds of iron and manganese combined. Nitric acid was distilled off it repeatedly; it was then boiled in acetic acid. The acetous solution was precipitated by potas. Nitric acid was again distilled off it, and it was again boiled in acetic acid. This process was repeated till nitric acid produced no further change. The different powders which could not be dissolved in the acetous acid were collected, mixed with a little oil, and heated red hot. The powder became black, and was attracted by the magnet. It was therefore oxyd of iron. It weighed 36 grains.

The acetous solution contained the oxyd of manganese: it was precipitated by an alkali, and, when dried, weighed 12.5 grains.

IX. Oxyd of Titanium and Iron.

Vauquelin analysed this ore as follows:

A hundred parts of the ore, reduced to a fine powder, and mixed with 400 parts of potas, were melted in a silver crucible for an hour and a half. When cool, the mixture was diluted with water; a powder remained of a brick red colour, which, when washed and dried, weighed 124 parts.

The watery solution had a fine green colour; when an excess of muriatic acid was added, it became red. By evaporation the liquor lost its colour. When evaporated to dryness, a salt remained, which was totally dissolved by water. From this solution carbonat of potas precipitated two parts, which had the properties of oxyd of titanium.

The 124 parts of residuum were boiled in a solution of pure potas for an hour. The solution was saturated with an acid, filtered, and carbonat of potas added, which precipitated three parts. These had the properties of oxyd of titanium.

The remainder of the 124 parts of residuum, which still was undissolved, was boiled with diluted muriatic acid. The liquor became yellow, and deposited 46 parts of a white powder, with a tint of red. This powder was soluble in sulphuric and muriatic acids: from these solutions, it was precipitated of a brick red colour by the infusion of nut galls; of a green colour by fulphuret of ammonia and prussiat of potas; and of a white colour by carbonat of potas and pure ammonia. A rod of tin made these solutions red; a rod of zinc made them violet. These 46 parts, therefore, are oxyd of titanium.

The muriatic solution, from which these 46 parts were deposited, formed, with prussiat of potas, a prussian blue; and ammonia precipitated from it 50 parts, which had the properties of yellow oxyd of iron.