sedimentary
Bauxite
Bauxite (Mixture including Gibbsite Al(OH)3, Boehmite γ-AlO(OH), and Diaspore α-AlO(OH))
Hardness: 1-3 on Mohs scale; Color: Reddish-brown, white, tan, or yellow; Luster: Dull to earthy; Structure: Pisolitic (pea-like) or massive/vesicular; Opaque; Specific gravity: 2.0-2.5.
- Hardness
- 1-3 on Mohs scale
- Color
- Reddish-brown, white, tan, or yellow
- Luster
- Dull to earthy
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Physical properties
Hardness: 1-3 on Mohs scale; Color: Reddish-brown, white, tan, or yellow; Luster: Dull to earthy; Structure: Pisolitic (pea-like) or massive/vesicular; Opaque; Specific gravity: 2.0-2.5.
Formation & geological history
Formed as a lateritic soil through the chemical weathering and leaching of silica from aluminum-rich rocks (like granite or basalt) in humid tropical/subtropical climates over millions of years.
Uses & applications
Primary ore of aluminum; used in the production of alumina for aircraft, construction, packaging, and the manufacture of abrasives and refractories.
Geological facts
Bauxite is not a mineral in the strict sense but a rock consisting of various aluminum hydroxide minerals. It was first discovered in 1821 by Pierre Berthier near the village of Les Baux in France.
Field identification & locations
Identify by its earthy appearance and reddish pitting (iron staining). Found commonly in Australia, Brazil, Guinea, and Jamaica. Collectors look for samples with distinct spherical 'pisolites' or interesting weathering textures.
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