Bauxite

Physical Properties

Hardness: 1-3 Mohs; Color: reddish-brown, white, tan, or grayish; Luster: dull to earthy; Structure: pisolitic (pea-like) or earthy; 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 (lateralization) of silicate rocks like granite, basalt, or shale. Typically Cenozoic to recent in age.

Uses & Applications

Primary ore of aluminum; used in the manufacture of abrasives, cement, chemicals, and refractory materials.

Geological Facts

Bauxite is not a mineral in the strict sense but a mixture of hydrous aluminum oxides. It was first discovered in 1821 by Pierre Berthier near the village of Les Baux in France.

Field Identification & Locations

Identify by its distinctive pisolitic (round, pea-sized) texture and clay-like or earthy appearance. It is commonly found in tropical belts such as Guinea, Australia, Brazil, and Jamaica. Collectors look for well-defined pisolites.

Identified on: 5/3/2026

Mode: Standard