The physico-chemical properties of cobalt allow for a hard wearing, wear-resistant metal with unique valency properties. These qualities make it unsubstitutable in a number of key sustainable and strategic applications.

Cobalt is a transition metal appearing in the fourth period of the periodic table between iron and nickel.

The ground state atom is 1s² 2s² 2p⁶ 3s² 3d⁷ 4s².

Cobalt’s most common valency is therefore Co²⁺, due to the removal of two 4s electrons. Other valencies also exist however, such as in the more complex salts. For example mixed valencies, Co²⁺ and Co³⁺, are present in Co₃O_4.

Cobalt is a shiny, grey, brittle metal with a close packed hexagonal (CPH) crystal structure at room temperature. At 421°C, the CPH crystal structure changes to a face centred cubic form (FCC).

The metal is rarely used as a structural material in the pure form but almost always as an alloy or a component of another system.