Emily Dickinson Lexicon

CO'BALT, n. [D. cobalt. This is said to be the G. kobold, a goblin, the demon of the mines; so called by miners, because cobalt was troublesome to miners, and at first its value was not known.]

A mineral of a reddish gray or grayish white color, very brittle, of a fine close grain, compact, but easily reducible to powder. It crystalizes in bundles of needles, arranged one over another. It is never found in a pure state; but usually as an oxyd, or combined with arsenic or its acid, with sulphur, iron, &c. Its ores are arranged under the following species, viz. arsenical cobalt, of a white color, passing to steel gray; its texture is granular, and when heated, it exhales the odor of garlic; gray cobalt, a compound of cobalt, arsenic, iron, and sulphur, of a white color, with a tinge of red; its structure is foliated, and its crystals have a cube for their primitive form; sulphuret of cobalt, compact and massive in its structure; oxyd of cobalt, brown, or brownish black, generally friable and earthy; sulphate and arseniate of cobalt, both of a red color, the former soluble in water. The impure oxyd of cobalt is called zaffer; but when fused with three parts of silicious sand and an alkaline flux, it is converted into a blue glass, called smalt. The great use of cobalt is to give a permanent blue color to glass and enamels upon metals, porcelain, and earthen wares. – Fourcroy. Encyc. Cleaveland. Cobalt-bloom, acicular arseniate of cobalt. Cobalt-crust, earthy arseniate of cobalt.