cobalt

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A hard, brittle metallic element, found associated with nickel, silver, lead, copper, and iron ores and resembling nickel and iron in appearance. It is used chiefly for magnetic alloys, high-temperature alloys, and in the form of its salts for blue glass and ceramic pigments. Atomic number 27; atomic weight 58.9332; melting point 1,495°C; boiling point 2,900°C; specific gravity 8.9; valence 2, 3. See Table at element.

Century Dictionary and Cyclopedia

1. n. Chemical symbol, Co; atomic weight, 58.8. A metal of a steel-gray color and a specific gravity variously given at from 8.52 to 8.95. It closely resembles nickel, the atomic weights of the two metals being the same, and their specific gravities nearly or quite the same. They have also very nearly the same ductility and tenacity, are almost always found in intimate association, and have in many respects a marked resemblance to iron, but are less fusible than that metal, and much less magnetic. Cobalt might be, and is to a very small extent, used for the same purposes for which nickel is used, especially for plating the surface of iron; but it is much rarer than nickel, is procured with more difficulty in the metallic form, and is consequently a dearer metal. The most important ores of cobalt are cobaltite, smaltite, and linnæite. (See these words.) Cobalt ores occur in a considerable number of localities, but nowhere in large quantity. The chief supply of the cobalt preparations comes from Saxony, Bohemia, Hesse, and Norway. The principal value of cohalt in the arts is due to the fact that its protoxid furnishes an intense and beautiful blue color, of importance in painting, and especially in the decoration of porcelain and glass. (See smalt and zaffre.) Also spelled kobalt.

Wiktionary

1. n. A chemical element (symbol Co) with an atomic number of 27.
2. n. Cobalt blue.

GNU Webster's 1913

1. n. (Chem.) A tough, lustrous, reddish white metal of the iron group, not easily fusible, and somewhat magnetic. Atomic weight 59.1. Symbol Co.
2. n. A commercial name of a crude arsenic used as fly poison.

WordNet 3.0

1. n. a hard ferromagnetic silver-white bivalent or trivalent metallic element; a trace element in plant and animal nutrition