22.—Cobalt Pyrites.
Occurs crystallized and massive; does not scratch glass easily; metallic lustre; tarnish, copper-red; powder, blackish-gray; brittle; heated on charcoal gives off sulphur fumes; heated with borax gives a blue glass; gravity 5.
Value.—An ore of cobalt, yielding twenty per cent.
Localities.—Usually found in slate or granite rocks with Copper Pyrites. Mineral Hill, Md.; Mine-la-Motte, Mo.