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DIALLAGE. 295 Cleavage, a, very perfect, usually rather curved; m, less distinct; e, b traces. Translucent...translucent on the edges. Lustre, on a pearly or silky inclining to metallic, on the other faces resinous or vitreous. Clove-brown...pinchbeck-brown, sometimes greenish or yellowish. Streak white. Slightly brittle, n = 6'0...8’0. g = 3’2...3-0. Melts with great difficulty before the blowpipe. Is not decomposed by acids. 11 Si, where II is magnesia and protoxide of iron. Analyses of bronzite a from the Stempel near Marburg, 6 from Ultenthal in the Tyrol, both by Kohler, c from Ultenthal, d from Stiria, both by Regnault:— abed Silica 57-19 56-81 55-81 66-41 Alumina 0'70 2-07 roo — Magnesia 32-07 29’68 30-37 31-60 Lime 1-30 2 19 — — Protoxide of iron .... 7-46 8'46 10 78 6-66 Protoxide of manganese . . 0'35 0'62 — 3-30 Mater 0-63 022 rso 2-38 In imperfect imbedded crystals; massive in granular aggre gations. Is found in serpentine on the Gulsen in Stiria, near Kupfer- berg in Bayreuth, Lettowitz and Goldenstein in Moravia, the Packer mountain in Lower Stiria, and the Lizard in Cornwall, on the Scefeld Alp in Ultenthal in the Tyrol; in basalt on the Stempel near Marburg, and on the Alpstein near Sontra in Hcssia. It is said to occur also at Yolpersdorf and Zobten- berg in Silesia, and in the Sierra Nevada in Spain. 164. DIALLAGE.—Diallage (in part) ; Phillips, Ilauy. PrismatischerSchiller-Spath (inpart); Mohs. Diallag; Ilaus- mann, llaidinger. Oblique. Supposed to be isomorphous with augite. Cleavage in two directions making right angles with each other; one perfect, the other imperfect; traces of cleavage in other directions. Fracture uneven, splintery. Opaque ; in Ve ry thin flakes translucent. Lustre on the plane of perfect cleavage pearly or silky, inclining to metallic. Grey, brownish- 8 r «y, brownish-green, sometimes light pinchbeck-brown. Streak White. 11 — 40. G = 32... 3-3.
