sedimentary
Bauxite
Aluminum ore / Hydrated aluminum oxides
Hardness varies from 1 to 3 on the Mohs scale depending on porosity and specific mineral mix; color is typically reddish-brown, pink, white, or tan; luster is dull or earthy; amorphous or pisolitic structure without distinct crystals.
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Physical properties
Hardness varies from 1 to 3 on the Mohs scale depending on porosity and specific mineral mix; color is typically reddish-brown, pink, white, or tan; luster is dull or earthy; amorphous or pisolitic structure without distinct crystals.
Formation & geological history
Formed by the intense weathering of aluminum-rich rocks (like granite, syenite, or limestone) in tropical and subtropical climates, where silica and other soluble components are leached away over millions of years.
Uses & applications
Primary ore for the production of aluminum metal via the Bayer and Hall-Héroult processes, and used in abrasives, refractories, and cements.
Geological facts
Bauxite is not a single mineral, but a mixture of hydrous aluminum oxides and hydroxides such as gibbsite, boehmite, and diaspore, along with iron oxides that give it its characteristic reddish color.
Field identification & locations
Can be identified in the field by its distinct pisolitic (pea-like) or oolitic texture, earthy smell when moistened, and reddish-brown color; commonly found in Australia, Guinea, Brazil, and Jamaica.
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