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328 a" 1)1 fwl •‘4 rru^y.yii.vp-i« Combinations, om.c.d.z, ox.d.c, odb, ocd.m, ocmzd.fi.g.b.x.l, oymzdlc. The faces a usually rough; o sometimes striated parallel to their intersections with z and m ; the faces b stri ated parallel to their intersections with m. Cleavage, c, very perfect; m, less easily obtained, often interrupted by fracture; a, yet less distinct; b, traces. Fracture imperfect conchoidal. Transparent.. .translucent. Lustre vitreous, inclining to pearly on the surfaces of perfect cleavage. Colourless, white, grey, blue, flesh-red. Brittle, h = 3-o...3'5. g = 3'85...4m Decrepitates when heated. Before the blowpipe on charcoal melts without difficulty in the outer flame into a white alealine bead, which, in the inner flame, spreads upon the charcoal and forms a hepar. When this hepar is dissolved in hydrochloric acid, evaporated to dryness and placed on a strip of paper SULPHATES. he ',a ib ic le Id' ic ’/ c V '0 <o' 90° o' 90 0 90 0 SO 57 101 64 78 49 28 43 67 26 22 22 44 44 52 4 104 8 23 9 46 18 lc 6° 6' ma 62 1 mm! 75 68 na 32 38 nri 114 44 zz' 67 25 zz" 90 34 z'z" 128 44 fa 69 27 fb 63 17 fa 34 47 qa 73 29 gb 68 39 qc 27 31 FIG. 620. b ya 45° 15' yb- 63 12 yc 66 43 yo 26 48 sa 33 66 sb 64 28 sc 69 15 x^a 41 38 xj,b 71 24 xpc 64 22 X a 40 7 Xb 75 60 X° 53 25 ■xa 33 41 xb 60 0 XC 69 23 xa 63 49 xb 75 24 xc 39 66 FIG. 521.