sedimentary
Bauxite
Alumina ore (Mixture of Gibbsite, Boehmite, and Diaspore)
Hardness: 1-3 Mohs; Color: Brown, reddish-brown, white, gray, or yellow; Luster: Dull to earthy; Crystal Structure: Amorphous (mixture of minerals); Specific Gravity: 2.0-2.6
- Hardness
- 1-3 Mohs
- Color
- Brown, reddish-brown, white, gray, or yellow
- Luster
- Dull to earthy
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Physical properties
Hardness: 1-3 Mohs; Color: Brown, reddish-brown, white, gray, or yellow; Luster: Dull to earthy; Crystal Structure: Amorphous (mixture of minerals); Specific Gravity: 2.0-2.6
Formation & geological history
Formed through the intense chemical weathering (lateritization) of rocks such as limestone, basalt, or granite in hot, humid tropical or subtropical climates.
Uses & applications
The primary ore used in the production of aluminum. Also used in abrasives, refractories, and chemicals such as aluminum sulfate.
Geological facts
Bauxite is not a single mineral but a rock essentially composed of hydrated aluminum oxides. It was first discovered in 1821 by geologist Pierre Berthier near the village of Les Baux in France.
Field identification & locations
Identify by its earthy, clay-like appearance, lack of crystalline structure, and often 'oolitic' or 'pisolitic' (pea-like) rounded texture. Commonly found in Australia, Guinea, and Brazil.
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