320 SILICATES. Combinations. Jen, ahn, abk, akmn, ahmnc, akmncbhdlurv. Cleavage, e very perfect, a less perfect, b indistinct. Trans lucent... opaque. Olive-green... black, h = e - o. Analyses of crystals from refinery cinder a (g = 3'700), b (o = 3 529), both by Walchner, c by Mitscherlich, d black opaque crystals (g = 4"08) which may be considered pseudomorphous, part of the protoxide of iron having been converted into the red oxide, by Percy; from copper slags e by Mitscherlich, / by Walchner:— Silica Protoxide of iron . Eed oxide of iron Magnesia . . . Oxide of manganese Alumina . . . Potash .... Phosphoric acid . Sulphuret of iron . a b c d e / 3296 32-35 31-16 29-60 30-93 29-25 61-24 62-04 67 24 48-43 69-07 6332 — — — 17-11 Cu 2-65 1-90 1-40 0-25 0-35 — 1-30 1'30 2-65 — 1-13 — 1-46 1-56 1-02 1-28 — 1-24 0-20 0-29 (Ca 0-47) — 0-18 — — — 1-34 — — — — 1-61 — — 180. TEPIIEOIT.—Tephroit; Mohs, Hausmann, Ilaidinger. Cleavage in two directions, making right angles with each other. Fracture uneven...imperfect conchoidal. Lustre ada mantine. Ash-grey. Acquires a brown or black tarnish. Streak ash-grey, h = 5-5. g = 4-06...4-12. Before the blowpipe melts very easily into a brown or black slag. With borax in the outer flame fuses into a glass which is violet while warm, and becomes red on cooling. Is decom posed by hydrochloric acid forming a jelly of silica. Mn 2 Si, silica 30 - 22, protoxide of manganese 69'78. Analyses by Thomson and Eammelsberg:— Silica 29'64 28’Gfl Protoxide of manganese . . 66 4 60 G8 - 88 Protoxide of iron .... 0’92 2 92 Water 270 Is found in cleavable and granular masses with franklinite at Franklin in New Jersey. r7-^r> ^I^LEMITE.—Willemine; Beudant. Brnchytyper m aryt; Mohs. Willemit; Hausmann, Ilaidinger. Ehombohedral. 100,111 = 30° 7'. 0 111, a 011, b 2II, r 100, 8 111.
