GIBBSITE. 271 145. HYDEAEGILLITE. — Hydrargylite ; Dufrenoy. Hydrargillit; Hausmann, Haidinger. Ehombohedral. o 111, a Oil, b 211. ao 90° o' ad 60 0 Id 30 0 W 60 0 Combination, oba. The faces a stri ated parallel to their intersections with b. Cleavage, o, perfect. Lustre, on a vitre ous; on o pearly, bright. Colourless, light re ddisli-white • H = 2'5...3'0. G = 2’340...2'387. In the matrass yields water. Before the blowpipe becomes white and opaque, exfoliates and shines with a very bright light, without melting. With solution of cobalt becomes blue. Yields a colourless transparent glass with borax and salt of phosphorus. In fine powder soluble with difficulty in hot sulphuric or hydrochloric acid. A1IP, alumina 6o-65, water 34-46. Analyses of hydrargillite a from Schischimskaja Gora by Hermann, b from Cidade d’Ouro Preto by v. Kobell a b Alumina ® 4 ' 03 65 8 Phosphoric acid.... l‘43 Water 34-54 34'4 Is found in very small crystals and granular and scaly masses at Achmatowsk near Slatoust in the Ural, with granular and crystallized magnetite; Cidade d’Ouro Preto in the Brazils; Hiehmond in Massachusetts. 146. GIBBSITE.— Gibbsite; Phillips. Gibbsit; Mobs, Hausmann, Haidinger. Feebly translucent. Dull. Greenish, greyish, yellowish- white. 'Brittle. 1I = 3-0. G = 2-20... 2'44. In the matrass yields much water, and diminishes in volume. Before the blowpipe in the forceps shines brightly, but does not melt. With solution of cobalt becomes blue. With boracic acid and iron wire yields phosphuret of iron. Is not soluble in hoiling hydrochloric acid. K 4 BIG. 297.