sedimentary
Bauxite
Bauxite (Al(OH)3 mixed with Fe2O3 and clay minerals)
Hardness: 1-3 (Mohs scale), Color: Reddish-brown, white, or yellow, Luster: Dull to earthy, Crystal Structure: Amorphous/microcrystalline, Specific Gravity: 2.0-2.5
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Physical properties
Hardness: 1-3 (Mohs scale), Color: Reddish-brown, white, or yellow, Luster: Dull to earthy, Crystal Structure: Amorphous/microcrystalline, Specific Gravity: 2.0-2.5
Formation & geological history
Formed through the intense chemical weathering of rocks (like granite or basalt) in hot, humid tropical or subtropical climates. It is a residual soil highly enriched in aluminum hydroxides.
Uses & applications
The primary ore for the production of aluminum. Also used in the manufacturing of abrasives, refractories, and chemical industries for water treatment and papermaking.
Geological facts
Bauxite is not technically a mineral but a rock composed mainly of aluminum-bearing minerals like gibbsite, boehmite, and diaspore. It is named after the village Les Baux in southern France where it was first discovered in 1821.
Field identification & locations
Identify in the field by its characteristic pisolitic (pea-shaped) or earthy structure and its association with deeply weathered red tropical soils (laterites). Commonly found in Australia, Guinea, Brazil, and Jamaica.
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