Cobalt was discovered in 1735. It occurs in cobaltite, smaltite, erythrite, and other minerals and is a by-product of processing nickel, silver, lead, copper, and iron ores.
Cobalt is a brittle, hard metal that ordinarily exists as a two-allotrope mixture. The artificial Cobalt-60 is an important source of gamma rays and used as a radiotherapeutic agent.
In alloys, it is used for high-speed, heavy-duty, high-temperature cutting tools and dies, in magnetic and stainless steels, and in jet turbines and gas turbine generators.
Cobalt salts produce brilliant hues and inks and permanent blue colors in porcelain, glass, pottery, tiles, and enamels. Cobalt compounds can be used to treat mineral deficiencies in animals.