sedimentary

Bauxite

Al2O3·2H2O (principally composed of gibbsite, boehmite, and diaspore)

AI-generated identification · may be incorrect

Hardness: 1-3 on Mohs scale; Color: Reddish-brown, tan, or yellow; Luster: Dull to earthy; Crystal structure: Amorphous or microcrystalline; Cleavage: None; Pisolitic/Oolitic texture (pea-sized round inclusions).

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

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the intense chemical weathering of rocks in tropical or subtropical climates with high rainfall, where silica is leached out and aluminum oxides are concentrated. Most deposits are of Cenozoic age.

Uses & applications

Primary ore of aluminum; used in the production of alumina (aluminum oxide) for industry, abrasives, refractories, and chemical processes.

Geological facts

Bauxite is named after the village of Les Baux in southern France, where it was first identified in 1821. It is not technically a single mineral but an aluminum-rich sedimentary rock also known as a 'laterite'.

Field identification & locations

Identify by its distinctive 'pea-like' or round pisolitic texture and earthy appearance. Found commonly in Guinea, Australia, Brazil, and Jamaica. Collectors look for pieces with well-defined, contrasting pisolites.