boehmite

Boehmite is a mineral with the chemical formula AlO(OH), also known as aluminum oxide hydroxide. It is one of the aluminum oxyhydroxide minerals and occurs in natural bauxite deposits, laterites, and alteration zones of aluminous rocks, especially where dehydration or hydrothermal activity has occurred.

Crystalline boehmite is typically white to colorless and forms microcrystalline masses, scales, or fibrous aggregates. It commonly coexists with other aluminum hydroxide minerals such as diaspore and gibbsite.

Geologically, boehmite forms by the alteration or dehydration of aluminum hydroxides and is a common constituent in bauxitic ores. It can also crystallize from hot spring deposits and hydrothermal environments.

Industrially, boehmite is a major precursor in the production of alumina. In the Bayer process, bauxite containing boehmite is digested and refined to alumina. Upon heating (calcination), boehmite loses water and converts first to gamma-alumina and then to alpha-alumina (corundum).

It is also used as a catalyst support, adsorbent, and filler due to its high surface area and porosity. Synthetic boehmite is employed to prepare alumina-based ceramics, coatings, and catalysts.