sedimentary
Bauxite
Hydrated aluminum oxides (mixture of gibbsite, boehmite, and diaspore)
Hardness: 1-3 Mohs; Color: Brown, red, yellow, or grey; Luster: Dull/earthy; Pisolitic (pea-like) structure; Opaque; Specific gravity: 2.0-2.5
- Hardness
- 1-3 Mohs
- Color
- Brown, red, yellow, or grey
- Luster
- Dull/earthy
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Physical properties
Hardness: 1-3 Mohs; Color: Brown, red, yellow, or grey; Luster: Dull/earthy; Pisolitic (pea-like) structure; Opaque; Specific gravity: 2.0-2.5
Formation & geological history
Formed as a residual soil (laterite) through the chemical weathering of aluminum-rich rocks in tropical or subtropical climates with high rainfall and good drainage.
Uses & applications
Primary ore of aluminum; used in the production of alumina (aluminum oxide), refractories, abrasives, and chemicals.
Geological facts
Bauxite isn't technically a mineral but a rock composed mainly of aluminum hydroxide minerals. It was first discovered in 1821 by Pierre Berthier near the village of Les Baux in France.
Field identification & locations
Identified by its distinctive pisolitic (spherical, pea-shaped) grains and earthy appearance. Found in tropical regions like Australia, Guinea, Brazil, and Jamaica. Collectors look for well-defined pisoliths.
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