| Gibbsite | |
|---|---|
 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 |
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).
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
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b c d Wefers, Karl; Misra, Chanakya (1987). Oxides and hydroxides of aluminum. Alcoa Research Laboratories. OCLC 894928306.
- ^ N.N. Greenwood and A. Earnshaw, "Chemistry of Elements", 2nd edition, Butterworth and Heinemann, 1997