Ores of Cobalt
Smaltite, Co(Fe, Ni) As2, Co . 28, As . 72.—H = 5.5, G = 6.37-7.30. Color, tin-white or steel-gray. Lustre, metallic. When heated to redness in an ignition tube it yields a sublimate of metallic arsenic. Before the Bp. on Ch. it fuses readily, with emission of arsenical fumes, to a grayish black magnetic globule. This globule may be examined for iron, cobalt, and nickel with the borax bead.
Cobaltite, CoS2 + CoAs2, Co . 36, As . 45, S . 19.—H = 5.5, G = 6.0-6.3. Color, silver-white tinged with red. Metallic lustre. Before the Bp. on Ch. fuses easily, with emission of copious arsenical fumes, to a gray magnetic globule. Remains unchanged in the ignition tube.
Linnaeite, (Co, Ni)3S4, (Co, Ni)58, S . 42.—H = 5.5, G = 4.8-5.0. Color, bright steel-gray, sometimes reddish. Lustre, metallic. Crystallizes in the regular octahedron. Before the Bp. on Ch. fuses to a metallic globule which is attracted by the magnet. With borax bead gives reaction for cobalt.
Erythrite, Co3O8As2 + 8 H2O, As2S5 . 38.4, CoO . 37.6, H2O . 24.0.—
H = 1.5-2.0, G = 2.95.
Color, crimson to peach-red. When crystallized, of pearly lustre, but frequently dull and earthy. Heated in ignition tube gives off water, and color changes to blue or green. Before the Bp. on Ch. in R. F. it emits arsenical fumes and melts to a dark gray globule which with the borax bead reacts for cobalt.