sedimentary
Bauxite
Bauxite (principal ore of aluminum, primarily Al(OH)3)
Hardness: 1-3 Mohs; Color: reddish-brown, white, tan, yellow; Luster: dull to earthy; Structure: Pisolitic (pea-sized round grains) or massive; Specific Gravity: 2.0-2.5.
- Hardness
- 1-3 Mohs
- Color
- reddish-brown, white, tan, yellow
- Luster
- dull to earthy
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Physical properties
Hardness: 1-3 Mohs; Color: reddish-brown, white, tan, yellow; Luster: dull to earthy; Structure: Pisolitic (pea-sized round grains) or massive; Specific Gravity: 2.0-2.5.
Formation & geological history
Formed by the intense chemical weathering of rocks in tropical or subtropical climates with high rainfall, leading to the leaching of silica and accumulation of aluminum oxides and hydroxides.
Uses & applications
Primary ore used for aluminum production; also used in refractories, abrasives, and the chemical industry.
Geological facts
Bauxite is not a mineral but a rock composed mainly of aluminum minerals like gibbsite, boehmite, and diaspore. It was first discovered in 1821 in Les Baux, France.
Field identification & locations
Identify by its distinctive 'pisolitic' texture, containing small round spheres. Found commonly in Australia, Guinea, Brazil, and Jamaica. Collectors look for well-defined pisolites or unusual coloration.
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