sedimentary

Bauxite

Bauxite (Principal ore of aluminum; mixture of minerals including Gibbsite Al(OH)3, Boehmite and Diaspore AlO(OH))

Hardness: 1-3 on Mohs scale; Color: Reddish-brown, yellow, tan; Luster: Dull to earthy; Crystal Structure: Amorphous/massive with oolitic or pisolitic (pea-sized) structures; Specific Gravity: 2.0-2.5.

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

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as a residual soil (laterite) through the intense chemical weathering of rocks in tropical or subtropical climates with high rainfall that leaches out silica. Typically Cenozoic in geological age.

Uses & applications

Primary source for aluminum production; also used in abrasives, refractories, and chemical industries. Occasionally polished for lapidary use due to its unique 'pea-stone' pattern.

Geological facts

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

Field identification & locations

Identify in the field by its distinct pisolitic (circular/nodular) texture and earthy, clay-like feel. Commonly found in Australia, Guinea, Brazil, and Jamaica. Collectors look for pieces with well-defined, contrasting circular structures.

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