Cobalt

(Synop., § 130), n. [Ger. kobalt, kobelt, kobolt, kobel, from kobold, M. H. Ger. kobolt, goblin, demon of the mines, L. Lat. cobaltus, from Gr. κώβαλος, knave; so called by miners, because cobalt was a poisonous metal and troublesome to miners.] (Metal.) A metal of a reddish-gray color, brittle, difficult of fusion, and having a specific gravity of about 7.8. It has not been found native, but is usually combined with arsenic, or its acid, with sulphur, iron, and nickel. The ores of metallic luster are white, grayish, or very slightly reddish. Its oxides are used in the manufacture of glass, to produce the blue varieties called smalt. Dana.

Cobalt-bloom, acicular arseniate of cobalt.—Cobalt blue, a compound of phosphate of cobalt and alumina, forming a blue pigment, often used in the arts.—Cobalt-crust, earthy arseniate of cobalt.—Cobalt green, a preparation consisting of cobalt and iron, having a green color, resulting from the presence of the latter metal.