alumine fluatée alkaline, Haüy; cryone, haltoïde, Haidinger.

This rare mineral is of a snow-white colour. It was originally brought by a missionary from Greenland to Copenhagen, where, from its resemblance to the common varieties of the sulphate of barytes, it lay neglected for many years. At length Abildgaard, attracted by its peculiar ponderosity, was induced to undertake an examination, in which fluoric acid, hitherto known only as a component of fluor spar, presented itself along with alumine; but as a considerable residue remained unaccounted for, Klaproth repeated the investigation, and discovered the presence of thirty-six per cent. of soda.

Of the geognostic relations of this interesting mineral nothing was known till the late Sir Charles Giesecke was induced, by his ardent desire for the prosecution of science, to take up his abode in those dreary regions, where he remained for upwards of eight years, and was enabled to visit the locality, which he found situated on the west coast of the peninsula, in a fiord or arm of the sea, denominated Arksut, near a place called Ivilket, where it occurs in two contemporaneous beds disposed in gneiss, nearly parallel to each other, and at no great distance.

The upper bed contains the fine white cryolite, and appears to have been the only one noticed previous to Giesecke's visit. The specimens from the lower bed first introduced by him are not only a good deal stained by ferruginous matter, but contain imbedded, sparry iron ore, sometimes in large crystals, galena, pyrites, and also detached crystals of felspar and quartz.

Fragments of cryolite obtained by cleavage are too often called crystals; but nothing of the kind has hitherto been observed. Its cleavage, however, is very distinct after being well soaked in water; it is threefold, two of these forming rectangular prisms with very smooth surfaces, while the third is at right angles to these, and rougher. Its great fusibility, for it yields even to the flame of a candle, suggested to Abildgard the name of cryolite, taken from χρυσος, ice, and λίθος, a stone, which it has always retained. It contains, according to Klaproth,

| Component | Percentage | |-----------|------------| | Soda | 36 | | Alumine | 23.5 | | Fluoric acid and water | 40.5 |

and indicates a specific gravity of 2.949.