~Smaltite~, Co(Fe, Ni) As_{2}, 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~, CoS_{2} + CoAs_{2}, 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)_{3}S_{4}, (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~, Co_{3}O_{8}As_{2} + 8 H_{2}O, As_{2}S_{5} . 38.4, CoO . 37.6, H_{2}O . 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. ORES OF COPPER ~Native Copper, Cu.~-- H = 2.5-3, G = 8.5-8.9. Color, copper-red. Lustre, metallic. Occurs usually massive and very arborescent. Before the Bp. on Ch. it fuses, and if the heat is sufficiently high it assumes a bright bluish-green surface; on cooling it is covered with a coat of black oxide. In the borax bead it reacts for copper. ~Chalcopyrite~, CuFeS_{2}, Cu . 35, Fe . 30, S . 35.--H = 3.5-4, G = 4.1-4.3. Color, brass-yellow, often golden-yellow. Lustre, metallic. Occurs crystallized, but is generally found massive. Is easily scratched with a knife. Heated in an ignition tube decrepitates, and occasionally yields a faint sublimate of sulphur. Before the Bp. on Ch. it blackens, but becomes red again on cooling. Before the Bp. on Ch. with Na_{2}CO_{3} and KCN it is reduced, and the metals are obtained in separate masses. It reacts with the borax bead for copper and iron. ~Copper Glance~, Cu_{2}S, Cu . 80, S . 20.--H = 2.5-3.0, G = 5.5-5.8. Color, dark blue to steel-gray. Occurs in compact masses, often very shining. Before the Bp. on Ch. fuses to a globule which boils and emits glowing drops. Sulphur dioxide escapes abundantly, and the outer flame is colored blue. Before the Bp. on Ch. with Na_{2}CO_{3} yielding a metallic globule.