sedimentary
Bauxite (Aluminum Ore)
Hydrated aluminum oxides, primarily Al(OH)3, AlO(OH)
Hardness: 1–3 Mohs; Color: reddish-brown, white, tan, or yellow; Lustre: dull, earthy; Structure: pisolitic (pea-shaped) or massive; Cleavage: none; Specific Gravity: 2.0–2.5
- Hardness
- 1–3 Mohs
- Color
- reddish-brown, white, tan, or yellow
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Physical properties
Hardness: 1–3 Mohs; Color: reddish-brown, white, tan, or yellow; Lustre: dull, earthy; Structure: pisolitic (pea-shaped) or massive; Cleavage: none; Specific Gravity: 2.0–2.5
Formation & geological history
Formed as a residual mineral (laterite) through the chemical weathering of aluminum-rich rocks in tropical or subtropical climates over millions of years.
Uses & applications
Primary source of aluminum for the aerospace, automotive, and construction industries; also used in abrasives, refractories, and chemical processes.
Geological facts
Bauxite is not a single mineral but a mixture of minerals like gibbsite, boehmite, and diaspore. The aluminum manufacturing process (Bayer process) was discovered in 1887.
Field identification & locations
Identify by its 'pea-like' (pisolitic) rounded structures and light weight. Commonly found in tropical regions like Australia, Guinea, and Brazil. Collectors look for unique pisolitic clusters.
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