Characteristics: Steel-gray, shining, hard, ductile, somewhat malleable metal; ferromagnetic, with permeability two-thirds that of iron; has exceptional magnetic properties in alloys. It is attacked by dilute hydrochloric and sulfuric acids; it is soluble in nitric acid. Cobalt corrodes readily in air. Hardness: cast, 124 Brinell; electrodeposited, 300 Brinell. An important trace element in soils and necessary for animal nutrition. Cobalt has unusual coordinating properties, especially the trivalent ion. Noncombustible except in powder form.
Derivation: From ore concentrates by roasting followed (a) by thermal reduction by aluminum, or (b) by electrolytic reduction of solutions of metal; (c) by leaching, with either ammonia or acid in an autoclave under elevated temperatures and pressures and subsequent reduction by H.
Hazard: Dust is flammable and may cause an allergic reaction in sensitized individuals. Exposure limit: 0.02mg/m3.