Aluminium hydroxide

Aluminium hydroxide, Al(OH)₃, is found in nature as the mineral gibbsite (also known as hydrargillite) and its three much rarer polymorphs: bayerite, doyleite, and nordstrandite. Aluminium hydroxide is amphoteric in nature, i.e., it has both basic and acidic properties. Closely related are aluminium oxide hydroxide, AlO(OH), and aluminium oxide or alumina (Al₂O₃), the latter of which is also amphoteric. These compounds together are the major components of the aluminium ore bauxite.