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356 STLICATES. Murainsk, Miask and Adun-Tschilon in Siberia, Kamtskatka, Peru, Rozena in Moravia with lepidolite, Mucla in Asia Minor, Penig in Saxony, at Schneckenstein near Auerbach in Saxony of a wine-yellow colour, at Villa Rica in the Brazils of a deep yellow colour; with tin ore at Geyer, Ehrenfriedersdorf and Altenberg in Saxony, and Schlackenwald in Bohemia, with tin ore and apatite in veins in granite at St. Michael’s Mount and Huel Kind near St. Agnes in Cornwall, at Trumbull and Mid dleton in Connecticut, in granite in the Morne mountains in Ireland. In isolated crystals in alluvial soil at Eibenstock in Saxony, Fribus in Bohemia, Orio-Branco and the river Ita Inga in the Brazils, New South "Wales, Cairn Goram in Aberdeen shire. The less transparent variety (pyrophysalite) with fluor in granite veins at Finbo near Eahlun, and in boulders at Broddbo near Eahlun in Sweden, in gneiss at Fossum near Modum in Norway. Topaz from New South Wales, the Brazils and Scotland, sometimes contains cavities in which Sir David Brewster dis covered two fluids, one of which has an index of refraction = 1*211, and expands o*25 of its original volume on being heated from 10° to 27°. According to Mohs and Hausmann, ‘pycnite’ is a variety of topaz having the faces a, m, and a perfect cleavage parallel to the face c, with planes of union sometimes parallel and some times making an angle with c. Fracture imperfect conchoidal ...uneven. Translucent...translucent on the edges. Lustre on the cleavage planes vitreous, on the surfaces of fracture feeble. Yellow, green, red, grey. Streak white, u = 7*6. g = 3*494...3*636. Pyroelectric. Infusible before the blowpipe, but blisters more readily than topaz. Analyses of pycnite from Altenberg, a by Berzelius, b by Eorchhammer:— Is found in parallel columnar aggregations, at Altenberg in Saxony, Schlackenwald in Bohemia, at Mauleon in France in steatite, at Kongsberg in Norway in mica slate. 199. LETTCOPIIANE.—Leucophane ; Dufrenoy. Leuko- phan; Hausmann, Haidinger. Anorthic. Fracture uneven. Transparent...translucent. Lustre vitre ous on cleavage planes, inclining to resinous on the surfaces of fracture. Pale greenish-grey...light wine-yellow. Streak white. a 38*43 51*00 17*10 b Silica . Alumina Fluorine 39*04 61*25 18*48