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BLACK BLENDE. 435 It Is almost always opaque, excepting the brownish- black variety, which is translucent on the edges and angles. The streak is intermediate between yellowish-grey and light yellowish-brown. It is semi hard. It is brittle. It is easily frangible. Specific gravity, 3.967 to 3.930, Gellert. 4.1665, Bris- son. 5.39S, auriferous from Nagyag, according to Von Muller. Constituent Parts. From Danemora. Bowallon. Zinc, 45 52 Oxide of Zinc, 53 Iron, 9 8 Iron, - 12 Lead, 6 - Arsenic, - 5 Arsenic, 1 - Sulphur, - 26 Copper, - 4 Water, - . ‘t Sulphur,, 29 26 ' 1 Silica, 4 6 100 Water, 6 4 Lampadius, ITandb. z. Ohcm. Annal. 100 100 d. Min. s. 282. Bergman, Opuscul t. iv. V p" 329. The black blende from Nagyag, besides zinc, iron, and manganese, contains a portion of auriferous silver. The lead and copper obtained from blende by ISergmnn, were probably derived from very minutely mixed galena or lead-glance and copper-pyrites, and the silica from the V(, 'n-stone. £ e 2 Gcognost is