354 SILICATES. ki 24° 47' kid 49 33 kn 62 41 kk" 105 21 ri 42 43 rd 85 26 ft 26 66 sc 34 7 oc 45 28 kc 63 48 me 90 0 r to O 23' r 47 14 sd 15 11 xd 28 30 qd 47 21 ss’ 30 22 ss" 59 28 XX 56 69 xx" 53 42 xc 41 4 xe 26 61 rc 69° 5' ry 39 54 oo' 38 63 oo” 78 8 qc 64 27 n 94 42 if 40 44 to 33 67 td 60 22 tt" 34 42 FIG. 372. FIG. 373. a' FIG. 374. Combinations, oml, ytnl. .c.o.z.ua, onml, oniml, fsxonrn csonmL.x.y, xonml, csoknymzlu.a.xi, acinymlukot, cidenymlkot wvr, mlo d. The faces c rough, sometimes striated parallel t their intersections with I ; m, z, I, u, v sometimes striated parallc to their intersections with each other. Cleavage. c t very per feet; i, n imperfect; m, I traces, especially in the varieties froii Scotland. Fracture conchoidal more or less perfect... uneven Transparent... translucent on the edges. Lustre vitreous. The indices of refraction of a white topaz for rays in planei parallel to a, perpendicular to a, c, parallel to c, and polarize! m those planes respectively, have been determined by Eudberg They are, for rays corresponding to Fraunhofer’s lines, H. G . F . E . 1-62745 1-62365 1-61914 1-61668 1-62539 1-62154 1-61701 1-61462 1-03506 163123 1-62052 1-62408
