sedimentary
Bauxite
Bauxite (Al2O3·2H2O)
Hardness: 1-3 (Mohs scale), Color: Reddish-brown, earthy white, or gray, Luster: Dull or earthy, Structure: Pisolitic (pea-like round grains), Specific Gravity: 2.0-2.5
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Physical properties
Hardness: 1-3 (Mohs scale), Color: Reddish-brown, earthy white, or gray, Luster: Dull or earthy, Structure: Pisolitic (pea-like round grains), Specific Gravity: 2.0-2.5
Formation & geological history
Formed through the intense chemical weathering (laterization) of aluminum-rich rocks in tropical or subtropical climates. It is the world's primary source of aluminum.
Uses & applications
Principal ore of aluminum; used in the production of alumina (Al2O3), which is then smelted into aluminum metal. Also used in abrasives, refractories, and chemicals.
Geological facts
The name comes from Les Baux in southern France, where it was first discovered in 1821. It is not technically a mineral but a rock composed mostly of aluminum hydroxide minerals like gibbsite and boehmite.
Field identification & locations
Identify by its distinctive 'pisolitic' (concretionary) texture, which looks like small peas cemented together. It is typically found in topsoil layers in tropical regions.
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