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Potash Soda Water LEPinOLITE. 391 n 0 P S' r 8 10-25 io-io 9-96] 1 8-87 1-05 155 — >13-68 1-45 — 2-43 3-42 ~ J 1 H.TH 4-12 — In p part of the iron is supposed to he in the state of pro toxide. This analysis appears to show that the substance of biotite, with which it agrees very nearly, is dimorphous. Mica is an essential ingredient of granite, gneiss, mica-slate, and is often found in fissures in those rocks, or crystallized in the cavities of the veins which traverse them. It also occurs in sand stones and various slate rocks, to which it imparts the property of cleavage; in veins and cavities in porphyry, basalt, dolomite, limestone, lava, and in matter ejected from volcanoes; investing or imbedded in andalusite, pinite, scapolite, tourma line and other minerals. Is found on Vesuvius, the Ilmen mountains, at Alabaschka near Mursinsk, the Adun-Tschilon mountains near Nertschinsk, a nd in very large transparent plates on the upper part of the courso of the Witim in Siberia, at Pargas in Finland, Narkseil- siak in Greenland, in various parts of the United States, at Pio Janeiro, in largo plates near Skutterud in Norway, in curved laminas at Skogbole in Kimito in Finland. Mica occurs occasionally in the slags of fumaoes. The clay sandstone forming the wall of iron furnaces has been found converted into a substance like mica. Some varieties of mica sufFer decomposition, and are converted into a steatitic substance. The figuro and angles given above are deduced from the measurements of a crystal from Vesuvius by W. Phillips. The crystal from the valley of Binnen, described by Marignac (Bibl. Univ. de Geneve. Ser. 4. T. 6. Supp. p. 301), is per haps a combination of the forms cbmuz, where u is 221 and z is u truncates the edge mr, and z is common to the zones ^ u > %C. uc — 94° 2(f, ub = 80° zb — 30° 6\ 225. LEPIDOLITE.—Lepidolite; Phillips. Mica (in part) ; Hauy. Hemiprismatischer Talk-Glimmer (in part) ; Mohs. Lepidolith; llausmnnn, Ilaidinger. Oblique ? & oio, c 001, m 110. mb 69° 30' mm 01 0 Combination, cbm. Cleavage, c, very perfect; m, b traces. s 4
