sedimentary

Bauxite

Bauxite (Al(OH)3, γ-AlO(OH), and α-AlO(OH))

AI-generated identification · may be incorrect

Hardness: 1-3 (Mohs scale); Color: Dull reddish-brown, tan, or white with mottled patterns; Luster: Earthy, dull; Structure: Pisolitic (pea-sized round grains) or massive; Cleage: None; Specific Gravity: 2.0-2.5

Hardness: 1-3 (Mohs scale)
Color: Dull reddish-brown, tan, or white with mottled patterns
Luster: Earthy, dull

Identified March 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the intense chemical weathering of rocks (like granite or basalt) in tropical or subtropical climates with high rainfall, which leaches away silica and leaves behind aluminum oxides. Age varies from Paleozoic to Cenozoic.

Uses & applications

Primary ore of aluminum used in construction, transportation (aerospace/automotive), and packaging. Also used in refractories, abrasives, and chemical production.

Geological facts

Bauxite is not a mineral but a rock composed mainly of aluminum-rich minerals like gibbsite, boehmite, and diaspore. The red color is typically due to iron oxide (hematite or goethite) impurities.

Field identification & locations

Identify by its 'pisolitic' texture (looking like it is made of small stuck-together pebbles) and earthy, clay-like appearance. Commonly found in Australia, Guinea, Brazil, and Jamaica. Collectors look for high-iron 'red' specimens or those with distinct large pisolites.