Bauxite is a mineral deposit rock formed by a mixture of metal oxides. It is the basic ore used in the production of alumina, which in turn is the raw material processed to obtain aluminium. Bauxites were formed during a geological period some 200 to 100 million years ago.

Alumina (an empirical name for aluminium oxide) may be either hydrated or anhydrous, depending on the degree to which it has been processed.

The aluminium produced by electrolysing anhydrous alumina is called primary cast aluminium, in order to be distinguished from secondary cast aluminium, which is recovered by recycling (re-melting) used aluminium products and waste.