sedimentary

Bauxite

Bauxite (Al2O3·2H2O)

Hardness: 1-3 Mohs scale; Color: Reddish-brown, yellow, white, or tan; Luster: Dull to earthy; Crystal Structure: Amorphous/microcrystalline; Cleavage: None; Specific Gravity: 2.0-2.5. Often exhibits a pisolitic (pea-like) concretionary structure.

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

Identified March 14, 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 away leaving behind aluminum oxides. Most deposits are from the Cenozoic era.

Uses & applications

Primary ore of aluminum; used in the production of alumina (aluminum oxide), abrasives, refractory materials, chemicals, and portland cement.

Geological facts

Bauxite is not technically a mineral but a rock composed of hydroxide minerals like gibbsite, boehmite, and diaspore. It was first discovered in 1821 by Pierre Berthier near the village of Les Baux in France.

Field identification & locations

Look for a distinct 'pisolitic' texture, resembling a mass of small round beads or peas stuck together. Commonly found in Australia, Guinea, Brazil, and Jamaica. It is often found in lateritic soil profiles in tropical regions.