Ores of Arsenic
Native Arsenic, As.—This contains traces of Sb, Ag, Fe, Co, and Ni.
H = 3.5, G = 5.7-5.8. Dark gray in color. Fracture tin-white, tarnishing rapidly. Volatilizes before the Bp. on Ch. without melting, giving white coating of arsenious acid and characteristic garlic odor. In ignition tube it sublimes, giving arsenical ring.
Realgar, AsS, As . 70, S . 30.—H = 1.5-2, G = 3.56. Bright red to orange-red color and resinous lustre. In an ignition tube it fuses and finally sublimes. The sublimate when cool is red and transparent. Fuses readily before the Bp. on Ch. and burns with pale yellowish flame, emitting gray-white fumes having garlic odor.
Orpiment, As2S3, As . 61, S . 39.—
H = 1.5-2.0, G = 3.4-3.5.
Lemon-yellow in color and resinous or pearly lustre. Sectile. Before the Bp. on Ch. behaves like realgar, but in an ignition tube it gives a dark yellow sublimate which is transparent.