Gibbsite
Species
Common · Al(OH)₃
Aluminium hydroxide, soft and pearly, with a strong clay smell when breathed on. It forms by weathering of aluminous rocks in tropical soils and is one of the three main minerals of bauxite, almost the only one in the lateritic bauxites of the tropics. It is also what the Bayer process precipitates from the caustic liquor when alumina is refined. Named for the collector George Gibbs.
Identity
- Formula
- Al(OH)₃
- Chemical class
- Oxide
- Also known as
- Hydrargillite
- Ore of
- Aluminum
Crystallography
- Crystal system
- Monoclinic
- Habits
- Tabular, Stalactitic, Earthy, Massive
- Fracture
- Uneven
Physical properties
- Mohs hardness
- 3
- Density
- 2.4 g/cm³
- Luster
- Vitreous, Pearly, Dull
- Colors
- colorless, white, gray, pale green, light red
- Transparency
- Transparent, Translucent
Geology
- Origins
- Sedimentary, Hydrothermal
- Host rocks
- Volcanic rock
- Associated minerals
- Diaspore, Boehmite, Corundum, Goethite
- Found in
- Bauxite, Laterite, Lateritic deposit
- Geography
- Brazil (Minas Gerais), Suriname (Paramaribo), India, Germany (Vogelsberg, Hesse), Russia (Zlatoust, Urals), USA
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Gibbsite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Gibbsite. Wikipedia.
- Bauxite. Wikipedia.
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