sedimentary

Bauxite

Bauxite (Al2O3·nH2O)

Hardness: 1-3 Mohs; Color: reddish-brown, tan, or creamy white; Luster: dull to earthy; Structure: pisolitic (pea-like) or massive; Cleavage: none; Specific Gravity: 2.0-2.5

Hardness: 1-3 Mohs
Color: reddish-brown, tan, or creamy white
Luster: dull to earthy

Identified June 17, 2026More sedimentary →

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Physical properties

Hardness: 1-3 Mohs; Color: reddish-brown, tan, or creamy white; Luster: dull to earthy; Structure: pisolitic (pea-like) or massive; Cleavage: none; Specific Gravity: 2.0-2.5

Formation & geological history

Formed as a residual soil in tropical and subtropical regions through the intense chemical weathering (lateritization) of aluminum-rich silicate rocks. Most deposits are of Cenozoic or Mesozoic age.

Uses & applications

The primary ore for aluminum production. Used in the manufacture of refractory materials, abrasives, chemicals, and cement.

Geological facts

It is named after its discovery site in Les Baux, France, in 1821. It is not a single mineral but a mixture of aluminum hydroxides like gibbsite, boehmite, and diaspore.

Field identification & locations

Identify in the field by its distinctive pea-like (pisolitic) grains, reddish-brown iron staining, and relatively low density. Commonly found in Australia, Guinea, Brazil, and Jamaica.