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LA.BRADOEITE. 375 clining to pearly on the faces of most perfect cleavage, and to resinous on the surfaces of fracture. Grey passing into yellow, red, green, white; ash-grey, smoke-grey, flesh-red. The colours of the face b sometimes changeable. The play of colours ap pears to he produced by a number of microscopic crystals of some other mineral, perhaps quartz, contained in the'labrado- rite. Streak white. Brittle, h = 6*0. a = 2*67... 2*76. _ Melts before the blowpipe rather more easily than felspar, into a colourless glass. In powder is completely decomposed oy concentrated hydrochloric acid. RS + A1S 2 , where It is principally lime and soda. Analyses of labradorite a from the island of St. Paul, b from Russia, both by Klaproth, c from a boulder in Brandenburg by Dulk, d from Campsie in Scotland, e from Milngavie near Glasgow, both by Le Ilunte, f from the lava of --Etna by Abich:— Silica. . . Alumina Red ox. iron Rime . . . Magnesia . Soda . . . Potash . . Plot ox. mang. Mater . . a b C d e / 66*75 66*00 64*68 64*87 62*34 53*48 20*60 24*00 27*87 27*89 29*97 28*46 1*25 6*25 — 0*31 0*87 1*00 11*00 10*26 12*01 10*60 12*10 9*49 — — — 0*18 — 1*74 4*00 3*50 6*40 6*05 3*97 4*10 — — 0*49 0*30 0*22 0*60 0*60 —_ _ 0'80 0-42 Analyses of labradorite g from Kijew by Segeth, h from Russgarden in the parish of Tuna in Dalarne by Svanberg, i from the doleritic porphyry of the Faroe islands (o = 2*67... 2*69) by Forclmmmer, k (g = 2*7i), I (a = 2*72), m (o = 2'705), all from Egersund by Kersten:— Silica. . . Alumina R^d ox. iron Rime . . Magnesia . Soda . . . Potash . . Mater . . g h i k 1 m 65*49 52*16 62*62 62*30 62*45 62*20 26*83 26*82 30*03 29*00 29*85 29*05 1*00 1*29 1*72 1*95 1*00 0*80 10*93 9*15 12*68 11*69 11*70 12*10 0*16 1*02 0*19 0*15 0*16 0*13 3*97 4*64 4*61 4*01 3*90 1 [ 0*30 1*79 0*60 0*60 J > 4*70 0*51 1*75 — — Analyses of labradorite n from Drummond in Canada by T. S. Runt, o from the porphyry of Tyfholms Udden near Holmen