Cobalt

Cobalt adds hardness to other metals with which it is alloyed.   One of these is iron and nickel, with other metals to form Alnico, a metal of very high magnetic strength with many important uses, from engines to musical instrument detectors ("pickups").   Extremely hard cobalt-based alloys with chromium and tungsten, called stellites, are used to make high-speed, high-temperature cutting tools and dies and surfaces subject to heavy wear.   Cobalt is used in electroplating because of its brightness, hardness and resistance to oxidation.   Cobalt-60, with a half-life of 5.27 years, is an important source of gamma rays used for tracers and radiotherapy. ^{Lide 4-9}   Cobalt has been used since ancient time as a paint pigment and dye ("cobalt blue").

Cobalt is essential to life because Vitamin B₁₂, cyano-cobalamine, an essential vitamin, is composed of a cyanide chemical group and a cobalt atom.   Soils should contain from 0.13 to 0.30 ppm of cobalt for animal nutrition.   When deficient, cobalt chloride, nitrate, sulfate and acetate are given to animals.

In plants, cobalt is required for nitrogen fixation in legumes and in root nodules of nonlegumes.   A deficit levels could result in nitrogen deficiency symptoms. ^{Morgan n.p.}

Salts of cobalt were used in ancient times for brilliant blue colors in porcelain, glass, pottery, tiles, and enamels, such as Sevre's blue and Thenard's blue.   Cobalt was discovered by Georg Brandt, a Swedish chemist, in 1737.   It was the first element isolated that was previously unknown.   Cobalt is found in cobaltite, smaltite, and erythrite ores and also in various nickel, silver, lead, copper and iron ores. ^{Lide 4-8}