sedimentary
Bauxite
Bauxite (Al(OH)3, γ-AlO(OH), and α-AlO(OH))
Hardness: 1-3 Mohs; Color: reddish-brown, pink, yellow, or grey; Luster: dull to earthy; Structure: Pisolitic (pea-like) or massive; Specific Gravity: 2.0-2.5
- Hardness
- 1-3 Mohs
- Color
- reddish-brown, pink, yellow, or grey
- Luster
- dull to earthy
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Physical properties
Hardness: 1-3 Mohs; Color: reddish-brown, pink, yellow, or grey; Luster: dull to earthy; Structure: Pisolitic (pea-like) or massive; Specific Gravity: 2.0-2.5
Formation & geological history
Formed as a residual soil in tropical and subtropical regions through the intense chemical weathering (laterization) of aluminum-rich rocks like granite or basalt.
Uses & applications
Primary ore of aluminum; used in the production of alumina for smelting, abrasives, refractories, and chemical industries.
Geological facts
Bauxite is named after the village of Les Baux in southern France where it was first discovered in 1821. It is not actually a single mineral, but a mixture of hydrous aluminum oxides.
Field identification & locations
Identify by its distinctive 'pisolitic' texture, where circular or oval nodules (pisolites) are visible in a finer-grained matrix. Found commonly in Guinea, Australia, Brazil, and Jamaica.
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