Cobalt is a silvery-blue transition metal with a melting point of 1495 degrees Celsius. It is one of 3 ferromagnetic transition metals. Many of its compounds are either red or blue. It is a light, strong, durable metal with a high melting point. It has oxidation states of -1, 0, +1, +2, +3, and +4. It was isolated in 1735 by Georg Brandt.

Cobalt is used in alloys in tools that need to be durable. Its compounds are also used to color glass or paints. It also used to be a component of invisible ink. Cobalt is also a part of vitamin B12.