sedimentary

Bauxite

Bauxite (Al2O3·nH2O)

AI-generated identification · may be incorrect

Hardness: 1-3 on Mohs scale; Color: Reddish-brown, white, tan, or yellow; Luster: Dull to earthy; Structure: Pisolitic (rounded, pea-like grains); Specific Gravity: 2.0-2.5.

Hardness: 1-3 on Mohs scale
Color: Reddish-brown, white, tan, or yellow
Luster: Dull to earthy

Identified March 17, 2026More sedimentary →

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Physical properties

Hardness: 1-3 on Mohs scale; Color: Reddish-brown, white, tan, or yellow; Luster: Dull to earthy; Structure: Pisolitic (rounded, pea-like grains); 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 silicate rocks like granite or basalt. It is typically found in geological profiles from the Cenozoic era.

Uses & applications

Primary ore of aluminum. Used in the production of alumina (Bayer process), refractories, abrasives, and chemical catalysts.

Geological facts

Bauxite is not technically a mineral but a rock composed mainly of aluminum oxide minerals like gibbsite, boehmite, and diaspore. The rounded 'peas' seen in specimens are called pisolites.

Field identification & locations

Identify in the field by its distinct pisolitic texture (concretionary structures) and earthy smell when damp. Common in Australia, Guinea, Brazil, and Jamaica. Collectors look for high-contrast pisolites.