sedimentary
Bauxite
AlOx(OH)3-2x (mixture of Gibbsite, Boehmite, and Diaspore)
Hardness: 1-3 Mohs; Color: reddish-brown, white, tan, yellow; Luster: dull to earthy; Crystal Structure: amorphous or microcrystalline; Specific Gravity: 2.0-2.5; Pisolitic (pea-sized) texture.
- 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; Crystal Structure: amorphous or microcrystalline; Specific Gravity: 2.0-2.5; Pisolitic (pea-sized) texture.
Formation & geological history
Formed by the intense chemical weathering of rocks (like granite or basalt) in tropical or subtropical climates through a process called lateritization, which leaches away silica leaving aluminum oxides.
Uses & applications
Primary ore of aluminum; used in the manufacture of aluminum metal, abrasives, refractories, and chemicals.
Geological facts
Bauxite was first discovered in 1821 by geologist Pierre Berthier near the village of Les Baux in southern France, from which it takes its name.
Field identification & locations
Identify by its distinctive 'pisolitic' texture resembling clusters of small peas or spheres; found commonly in Australia, Guinea, Brazil, and Jamaica. Collectors look for well-defined pisolites and varied coloration.
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