What is "gibbsite"

Gibbsite \Gibbs"ite\, n. [Named after George Gibbs.] (Min.) A hydrate of alumina.

n. (context mineral English) A mineral with monoclinic crystals, usually white but can have different colors, aluminum(oxygenhydrogen)₃.

n. white crystalline mineral consisting of aluminum hydroxide; a constituent of bauxite and a source of alumina

Gibbsite, Al(OH), is one of the mineral forms of aluminium hydroxide. It is often designated as γ-Al(OH) (but sometimes as α-Al(OH).). It is also sometimes called hydrargillite (or hydrargyllite).

Gibbsite is an important ore of aluminium in that it is one of three main phases that make up the rock bauxite. Bauxite is often thought of as a mineral but it is really a rock composed of hydroxide and oxyhydroxide minerals such as gibbsite, boehmite (γ-AlO(OH)), and diaspore (α-AlO(OH)), as well as clays, silt, and iron oxides and hydroxides.

Gibbsite has three named structural polymorphs or polytypes: bayerite (designated often as α-Al(OH), but sometimes as β-Al(OH)), doyleite, and nordstrandite. Gibbsite and bayerite are monoclinic, whereas doyleite and nordstrandite are triclinic forms.