Cryolite (Gr. ice, and , stone), a mineral so named from its fusibility in the flame of a candle. It is a compound of sodium, fluorine, and aluminum, and is used for the preparation of the metal aluminum. Large quantities are imported into England for this and other purposes from Greenland, where it was discovered by a missionary and carried to Copenhagen. It was supposed to be sulphate of barytes until examined by Abildgaard, who found it to contain fluoric acid. Klaproth afterward detected soda. It is a snow-white mineral, partially transparent, of vitreous lustre and brittle texture. Its hardness is 2.5; sp. gr. 3. It cleaves in three directions, two of which are rectangular. It occurs in veins in gneiss with pyrites and galena, and has been found at Arksut in western Greenland, and at Miyask in the Ural. At the former place it constitutes a mass 80 ft. thick and 300 ft. long, included between layers of gneiss and associated with argentiferous galena and copper and iron pyrites. - Cryolite is extensively employed in the United States in the manufacture of a white porcelain glass, and also in the preparation of caustic soda; 5,000 tons per annum are imported for these purposes.