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644 APPENDIX. which have been observed are -.—pm = 94° 20', pa = 64° o', py = 81° nearly, ya = 145° nearly, y, c, a are in the same zone. Cleavage, c, b, perfect; the cleavage c is interrupted by striaa where it intersects the junctions of the twin crystals. Trans lucent on the edges. Lustre vitreous. Reddish-grey...peach- blossom red. h = s-s...6-o. a=2‘763. Melts before the blowpipe into a colourless blebby glass. With borax fuses slowly into a transparent bead. Is found in granular limestone at Lojo in Finland, Tunaberg in Sweden and Bytown in Upper Canada. The crystals of lepolite are said to resemble those of oligoclase. ® 2 75...2 77. Melts with difficulty before the blowpipe into a transparent glass. In very fine powder is soluble in mineral acids. Indianite has two cleavages making with each other an angle of 94° 15'. More or less translucent.. White, grey, red. h == 7'°.. .7‘25. g == 2'668.. .2'742. Said to be infusible before the blowpipe. Gelatinizes with acids. Indianite is the matrix of corundum in India. Analyses of amphodelite a from Lojo by Nordenskibld, b from Tunaberg by Svanberg, of lepolite c from Lojo, d from Orijerfvi, both by Hermann, e,f of indianite by Laugier, y of indianite, n = 7-0...7-25, g = 2-668, by Brush J Silica . . . Alumina Red ox. iron Lime . . Magnesia . Soda . . . Water . . a b C d e / 9 45-80 44-55 42-80 42-60 42-00 43-0 42-09 36-45 3519 35-12 33-11 34-00 34-6 38-89 1-70 0 4 07 1-60 400 3’20 1-0 — 10-15 15-02 14-94 10-87 15-00 156 15-78 5-05 4-08 2-27 5-87 — — — — 1-50 1-69 335 2-6 4-08 1-85 0-59 1-56 1-50 1-00 1-0 — LOXOCLASE. — Oblique. Has the faces a cleavage, I, c, x, y, m, of felspar, ab = 90° o', cb = 90° o', ac = 63° 38', xa =65° 37', yc = 80° is'. Cleavage, c, very perfect; b, very dis tinct ; a, indistinct. Fracture uneven... conchoidal... splintery. Translucent. Lustre vitreous, inclining to resinous ; on c pearly. 11 nearly 6. g = 2609...2-620. Analysis by Plattner:—silica 63-50, alumina 20 29, red oxide of iron 0-67, potash 3-03, soda 8‘76, lime 3-22, magnesia trace, water and fluosilicic acid 1-23. Loxo- clase appears to have the chemical constitution of oligoclase with the form of felspar. Is found with graphite, calcite and diopside at Hammond in New York. compact FELSPAR, PITCIISTONE, PEARLSTONE, OBSIDIAN, PUMICE.—The first of these amorphous sub- s ances appears to be a mechanical mixture of felspar and quartz; the others probably result from their fusion with