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BIOTITE. 387 kyamte and staurolite; in beds of magnetite, towanite and glena; in veins of tm ore. Crystallized talc is found on tbe oAT- Q,? er *, a ? m T ^ e T J rol > St. Gotthard, tbe district I Salzburg, Stina, Sahla, Fablun and other places in Sweden na°A n r I? ? aV ^ a ’ Ka t h arinenburg in Siberia, in many parts of Scotland. The massive variety is found at Gopfersgriin near Wunsiedel in the Fichtelgebirge, pseudomorphous after ss ot SKoor “ d Boh “- Tnn 2 rM E10TIT , F rT Mica ( in P art ) ; klauy. Ehomboedrischer ialk-Ghmmer; Mohs. Biotit; Hausmann. Meroxen; Ilai- Ehombohedral. 100,111 = 70° o'. 0 a 01 b 1" 100, S 111, w 142, V 153, Z 175. ao 90° o' ad eo o ro 70 o FIG. 399. rr r so 108° 66 79 41 116 52 WO VO ZO 81 3 84 0 FIG. 400. FIG. 401. Combinations, oa, or, oaswvz. Cleavage, o, very perfect. Transparent...translucent; less so in a direction perpendicular to o than parallel to o. Lustre, o pearly inclining to metallic ; the other faces vitreous. Dark green, brown, passing into black. Streak white...pale greenish-grey. Sectile. In thin eaves elastic, u = 2‘0...2’5. o less hard than the other laces, o = 2-78...2-95. In tho matrass yields water and, usually, traces of hydro fluoric acid. Before the blowpipe melts with difficulty into a grey or black bead. Soluble in borax forming a glass coloured by iron. Is slightly attacked by hydrochloric acid. Is com pletely decomposed by sulphuric acid, leaving pearly scales of silica. _ K’Si J + AlSi, where It denotes Mg, K, Fe, and part of the ai is replaced by f*.
