COBALT, n. 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 red color, the former soluble in water. The impure oxyd of cobalt is called zaffer; but when fused with three parts of siliceous 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 earthern wares.

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.

1. A tough, lustrous, reddish white metal of the iron group, not easily fusible, and somewhat magnetic. Atomic weight 59.1. Symbol Co.
   
   

   * It occurs in nature in combination with arsenic, sulphur, and oxygen, and is obtained from its ores, smaltite, cobaltite, asbolite, etc. Its oxide colors glass or any flux, as borax, a fine blue, and is used in the manufacture of smalt. It is frequently associated with nickel, and both are characteristic ingredients of meteoric iron.

2. A commercial name of a crude arsenic used as fly poison.
   
   

   Cobalt bloom. Same as Erythrite. -- Cobalt blue, a dark blue pigment consisting of some salt of cobalt, as the phosphate, ignited with alumina; -- called also cobalt ultramarine, and Thenard's blue. -- Cobalt crust, earthy arseniate of cobalt. -- Cobalt glance. (Min.) See Cobaltite. -- Cobalt green, a pigment consisting essentially of the oxides of cobalt and zinc; -- called also Rinman's green. -- Cobalt yellow (Chem.), a yellow crystalline powder, regarded as a double nitrite of cobalt and potassium.