aqua-marine; émeraude limpide; beril. This mineral, as was originally conjectured by Pliny, is a variety of the emerald, being distinguished from the latter only by its colour. The term emerald is consequently confined to that variety which presents its own peculiar colour, namely, the rich deep emerald green; while that of beryl is given to all the other varieties, as the sea-green, pale-blue, golden-yellow, and colourless.

Of the emerald we shall treat under the proper head; for although it is identically the same mineral, it sometimes leads to confusion to treat beryl and emerald under the same denomination. For instance, Haiii, speaking of emerald in the first edition of his Traité, says that the largest crystal he ever saw measured six inches in length and two in thickness, and that it came from Peru. In his second edition he mentions, as the largest he had ever met with, a crystal of the same dimensions which came from Santa Fé; and immediately passes on to a description of the Siberian emeralds. He considered them as the same mineral species. The large crystal which he mentions is in the royal collection at Madrid, and is the true emerald. This points out the propriety of confining the name of emerald to the beautiful deep green gem, while that of beryl may be bestowed on all the other varieties. These are by no means uncommon. They occur in veins and drusy cavities in granite, and are found in France, at Nantes, and at Limoges; in Ireland, in the mountains of Wicklow and the county of Down; in Scotland, in the district of Cairngorm; at Schlaggenwald in Bohemia; at Swezel in Bavaria; at Brodho in Sweden; and in the Altai and Oural Mountains in Siberia, where they seem to exist in greater abundance and in larger groups and crystals than in any other quarter of the world, always excepting the varieties from Limoges. In Peru and Brazil, there are localities well known as producing beryls. In the northern states of America many of these have been indicated by the American mineralogists. Some very fine pale green-coloured beryls have been imported from the district of Ghellan, in Hindustan, 300 miles S.W. of Madras. This mineral, therefore, is not unsparingly distributed over the globe; and it affords one of the greatest embellishments to the cabinet of the mineralogist, while it yields an abundant supply to the jeweller for the exercise of his taste in producing a variety of ornaments.

Although Pliny was the first who suggested the identity of the emerald and the beryl, it was left to Romé de Lisle to put this conjecture to the proof. Pallas, who first discovered the beryl in Siberia, sent some specimens for examination to that crystallographer, who immediately observed the perfect similarity of form between some of these and certain crystals of emerald then in his possession; which circumstance, joined to the hardness and specific gravity of the two objects, soon satisfied him that they were of the same species. This was one of the first triumphs of crystallography; and it was soon after confirmed by the labours of the chemist. The analysis of this mineral is peculiarly interesting, as will be seen by the following comparative table:

| | Emerald | Beryl | |-------|---------|-------| | Silica | 64-50 | 68-50 | | Alumina| 16-00 | 15-75 | | Glucine| 13-00 | 12-50 | | Lime | 1-60 | 0-25 | | Ox. Chrom. | 3-25 | 0-30 | | Iron | 1-0 | 1-0 | | Loss | 1-15 | |

The largest mass of precious beryl known to mineralogists is an aqua-marine belonging to the late Don Pedro: it is nearly as large as the head of a calf, and weighs 225 ounces Troy, or 18 lb. 9 oz. On one side there are slight indications of the plane of a crystal; but it is otherwise entirely water-worn. Its surface is consequently dull; but beneath it the mass is perfectly clear and transparent, and, large as it is, without a flaw. It presents a beautiful pale bottle-green colour. The largest crystals known are those from Limoges in France, and Brodho in Sweden. At the former place they occur in a vein of quartz in granite, sometimes very perfect, and a foot in diameter; and there is a crystal from the latter place in the museum of Stockholm which weighs upwards of eighty pounds. These large crystalline masses are generally very coarse in their texture, and present an earthy aspect, somewhat like decomposed felspar.