The Collaborative International Dictionary of English v.0.48:
Cobalt \Co"balt\ (k[=o]"b[o^]lt; 277, 74), n. [G. kobalt, prob.
fr. kobold, kobel, goblin, MHG. kobolt; perh. akin to G.
koben pigsty, hut, AS. cofa room, cofgodas household gods,
Icel. kofi hut. If so, the ending -old stands for older
-walt, -wald, being the same as -ald in E. herald and the
word would mean ruler or governor in a house, house spirit,
the metal being so called by miners, because it was poisonous
and troublesome. Cf. Kobold, Cove, Goblin.]
1. (Chem.) A tough, lustrous, reddish white metal of the iron
group, not easily fusible, and somewhat magnetic. Atomic
weight 59.1. Symbol Co.
Note: 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
Cobalt yellow (Chem.), a yellow crystalline powder,
regarded as a double nitrite of cobalt and potassium.