Gibbsite, Al(OH)3, is one of the mineral forms of aluminium hydroxide ). It is also sometimes called hydrargillite (or hydrargyllite).
Gibbsite is an important ore of aluminium in that it is one of three main phases.
Gibbsite has three named structural polymorphs : bayerite (designated often as α-Al(OH)3,:2 but sometimes as β-Al(OH)3), doyleite, and nordstrandite. Gibbsite can be monoclinic or triclinic, while bayerite is monoclinic.:13 Doyleite and nordstrandite are triclinic :13