sedimentary
Bauxite (Concretionary)
Bauxite (Al(OH)3, AlO(OH))
Hardness: 1-3. Color: Red-brown with cream/white interior patches. Luster: Dull or earthy. Structure: Pisolitic or concretionary nodules. Cleavage: None. Specific Gravity: 2.0-2.5.
- Hardness
- 1-3
- Color
- Red-brown with cream/white interior patches
- Luster
- Dull or earthy
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Physical properties
Hardness: 1-3. Color: Red-brown with cream/white interior patches. Luster: Dull or earthy. Structure: Pisolitic or concretionary nodules. Cleavage: None. Specific Gravity: 2.0-2.5.
Formation & geological history
Formed by intense chemical weathering (lateritization) of aluminum-rich rocks in tropical or subtropical climates, often found in ancient soil horizons.
Uses & applications
The primary ore of aluminum used in aerospace, construction, packaging, and transportation industries.
Geological facts
Bauxite is named after the village of Les Baux in France where it was first identified in 1821; it is not a single mineral but a mixture of hydrous aluminum oxides.
Field identification & locations
Look for rounded, pea-shaped nodules (pisolites) with reddish-brown staining in tropical weathering zones or sedimentary basins. Common in Australia, Guinea, and Brazil.
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