sedimentary

Bauxite

Bauxite (Al2O3·nH2O)

Hardness: 1-3 Mohs; Color: reddish-brown, tan, or gray; Luster: earthy/dull; Structure: pisolitic (pea-like) or massive; Specific Gravity: 2.0-2.5.

Hardness: 1-3 Mohs
Color: reddish-brown, tan, or gray
Luster: earthy/dull

Identified May 25, 2026More sedimentary →

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Physical properties

Hardness: 1-3 Mohs; Color: reddish-brown, tan, or gray; Luster: earthy/dull; Structure: pisolitic (pea-like) or massive; Specific Gravity: 2.0-2.5.

Formation & geological history

Formed by the chemical weathering of aluminum-rich rocks in tropical or subtropical climates with high rainfall. It is a residual soil (laterite) often from the Tertiary period or older.

Uses & applications

Primary ore for aluminum production. Used in abrasives, refractories, chemicals, and as a flux in steel making.

Geological facts

Named after the village Les Baux in France where it was first discovered in 1821. It is not a single mineral but a mixture of hydrous aluminum oxides.

Field identification & locations

Identified by its distinctive rounded, pea-sized structures called pisolites. Found globally in tropical belts like Australia, Guinea, and Brazil. Collectors look for well-defined pisolitic textures.