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52 SCHORL FAMILY. Constituent Parts. Saxon. Brazilian. Brazilian. Silica, 35. 44.5 29. Alumina, 59. 47.5 50. Fluoric acid, 5. 7. 19. Oxide of iron, 0.5 Loss, 1. 0.5 2. 100. 100. 100. Klap. b. 4. $. 160. Klap. ib. Vaiupudin, Annales du Mus. t. vi. p. 24. Geognostic Situation. It occurs in that particular mountain-rock denomina ted Topaz-rock; which is an aggregate of massive topaz, quartz, and schorl; having in the small a slaty, but in the large a granular texture; and in which there are fre quent small cavities, lined with crystals of topaz, quartz and schorl, and portions of lithomarge. It occurs in drusy cavities, in granite, along with beryl, and rock crys tal ; also in veins, which traverse primitive rocks, ac companied, in certain formations, with beryl, rock-crys tal, and iron-ochre, when the veins traverse granite; in others with tinstone, arsenical pyrites, sometimes copper pyrites, apatite, fluor-spar, quartz, steatite, when the veins traverse gneiss and mica-slate. It has been also discovered in nests, in transition clay-slate, along with red-coloured quartz, brown-spar, and selenite or gypseous spar; and it is found in rolled pieces in allu vial soil. Geographic
