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Gibbsite
Form of aluminium hydroxide, mineral / From Wikipedia, the free encyclopedia
Gibbsite, Al(OH)3, is one of the mineral forms of aluminium hydroxide. It is often designated as γ-Al(OH)3[2]: 2 (but sometimes as α-Al(OH)3[3]). It is also sometimes called hydrargillite (or hydrargyllite).
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Gibbsite | |
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![]() Gibbsite | |
General | |
Category | Hydroxide minerals |
Formula (repeating unit) | Al(OH)3 |
IMA symbol | Gbb[1] |
Strunz classification | 4.FE.10 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/n |
Identification | |
Mohs scale hardness | 2.5–3 |
Specific gravity | 2.35 |
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Gibbsite is an important ore of aluminium in that it is one of three main phases that make up the rock bauxite.
Gibbsite has three named structural polymorphs or polytypes: bayerite (designated often as α-Al(OH)3,[2]: 2 but sometimes as β-Al(OH)3)[citation needed], doyleite, and nordstrandite. Gibbsite can be monoclinic or triclinic, while bayerite is monoclinic.[2]: 13 Doyleite and nordstrandite are triclinic forms.[2]: 13