352 SILICATES. wa ua va za ca ea ra xa he nc dc be M nri dd f ma ba mm' fa 21° 38' 40 37 64 29 64 0 100 48 137 36 147 8 161 0 43 17 64 43 70 31 90 0 93 26 70 34 38 68 64 45 90 0 SO 30 62 17 PIG. 370. ml fa r qb pb lb pu 9 h gv yb kb ob sb ss tb tr ib 37° 43' 75 26 68 1 46 63 28 6 43 7 52 2 37 58 48 21 54 34 61 7 42 39 86 18 32 38 67 22 46 52 IX pa fa na Ba qc he ye fa le me ct’ cs' CO she FIG. 371. 43° 8' 56 66 74 27 96 13 116 24 65 3 39 43 48 33 60 40 76 27 94 35 111 62 125 50 136 13 30 12 Twins. Twin-face u. Cleavage, c. Fracture uneven... conchoidal. Transparent...translucent. Lustre vitreous in clining to resinous. Yellow of various shades...reddish-brown grey. Streak white, h = 0-5. g = 3-10...3-20. ’ In the open tube with salt of phosphorus yields the reaction of fluorine. Infusible before the blowpipe. Dissolves in salt of phosphorus leaving a skeleton of silica. With borax fuses slowly but completely into a clear glass slightly tinged by iron. Soluble in hydrochloric acid leaving a jelly of silica. Soluble in sulphuric acid which expels the fluorine. silica 37'28, magnesia 60 06, magnesium toxide of ^ron ^ 66 ' ° f th<3 ma S llesia ia replaced by pro-
