Bauxite is the most important aluminium ore. It consists largely of the minerals gibbsite Al(OH)3, boehmite γ-AlO(OH), and diaspore α-AlO(OH), together with the iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2.

Lateritic bauxites (silicate bauxites) are distinguished from karst bauxites (carbonate bauxites).

Calcined bauxite dust is regarded as a nuisance