sedimentary
Bauxite
Bauxite (Al2O3·2H2O)
Hardness: 1-3 Mohs; Color: reddish-brown, white, tan, gray; Luster: earthy, dull; Structure: pisolitic (concretionary) or massive; Specific Gravity: 2.0-2.5
- Hardness
- 1-3 Mohs
- Color
- reddish-brown, white, tan, gray
- Luster
- earthy, dull
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Physical properties
Hardness: 1-3 Mohs; Color: reddish-brown, white, tan, gray; Luster: earthy, dull; Structure: pisolitic (concretionary) or massive; Specific Gravity: 2.0-2.5
Formation & geological history
Formed by the intense chemical weathering of rocks in tropical or subtropical climates, which leaches away silica and results in the accumulation of aluminum oxides and hydroxides. Most deposits are Cenozoic or Mesozoic.
Uses & applications
The world's primary source of aluminum. Used in the production of aluminum metal, abrasives, refractories, and chemicals.
Geological facts
Bauxite is not technically a mineral but a rock composed mostly of aluminum minerals like gibbsite, boehmite, and diaspore. It was named after the village Les Baux in southern France where it was first identified.
Field identification & locations
Identified by its pea-like (pisolitic) rounded structures and reddish-brown earthy appearance. Found in Australia, Guinea, Brazil, and Jamaica. Collectors look for well-defined pisolites.
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