Cobalt is a chemical element; it has symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silvery metal.
Cobalt
A block of electrolytically refined cobalt (99.9% purity) cut from a large plate
Cobalt(II) chloride hexahydrate
Early Chinese blue and white porcelain, manufactured c. 1335
Chemical symbols are the abbreviations used in chemistry, mainly for chemical elements; but also for functional groups, chemical compounds, and other entities. Element symbols for chemical elements normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised.
Dalton's symbols for the more common elements, as of 1806, and the relative weights he calculated. The symbols for magnesium and calcium ("lime") were replaced by 1808, and that for gold was simplified.