Fact sheet
- Rock type: Residual sedimentary rock (regolith). Bauxite is a rock, not a mineral, an aggregate of aluminium hydroxides plus iron oxides, clay minerals, and titanium oxides.
- Principal aluminium-bearing minerals: Gibbsite, Al(OH)₃ (monoclinic); boehmite, γ-AlO(OH) (orthorhombic); diaspore, α-AlO(OH) (orthorhombic).
- Common accessory minerals: Hematite and goethite (Fe), kaolinite (clay), anatase and rutile (Ti).
- Bulk composition: Typically 40–60 % Al₂O₃, 10–30 % Fe₂O₃, 1–10 % SiO₂, 1–5 % TiO₂, plus structural water.
- Hardness of the Al-hydroxide phases (Mohs): Gibbsite 2.5–3.5, boehmite 3–3.5, diaspore 6.5–7.
- Colour: White to cream where iron-poor; ochre, red, and red-brown where hematite-rich. Pisolitic textures are common.
- Genetic types: Lateritic bauxite (~88 % of global resources), karst bauxite (~11.5 %), and a minor sedimentary “Tikhvin” type.
- Top producers (2024): Guinea, Australia, China, Brazil, Indonesia, India.
- Largest reserves: Guinea holds the largest listed bauxite reserves at roughly 7.4 billion tonnes. Other major reserve holders include Australia, Vietnam, Indonesia, Jamaica, and Brazil.
- Primary use: Feedstock for alumina and aluminium metal. Roughly 85% of world bauxite production is used to make alumina by the Bayer process; most of that alumina is then smelted to aluminium by the Hall–Héroult process.
A rock named after a Provençal village
In March 1821, the French mining engineer Pierre Berthier was sent to examine a reddish, iron-stained outcrop near the village of Les Baux-de-Provence in the Bouches-du-Rhône. His employers expected an iron ore. Berthier’s analysis, published the same year in the Annales des Mines, showed instead that the rock was dominated by hydrated alumina; the first time a hydrated aluminium oxide had been documented from a European deposit. He simply called it l’alumine hydratée des Beaux. The name beauxite was introduced by Armand Dufrénoy in the mid-nineteenth century and later revised to the modern spelling bauxite by Henri Sainte-Claire Deville in 1861. Industrial exploitation followed almost immediately, and France remained the world’s leading producer until 1913.
What bauxite actually is
Bauxite is not a mineral and has no crystal system of its own. It is a polymineralic, residual rock: the upper, aluminium-enriched horizon of a deeply weathered profile. Three aluminium-hydroxide minerals dominate, and their proportions reflect the depth, temperature, and age of the weathering system: gibbsite in young, low-temperature lateritic profiles; boehmite in older or slightly buried deposits where partial dehydration has occurred; diaspore in deeply buried or low-grade metamorphosed bauxites. The accompanying iron oxides give bauxite its characteristic red and ochre tones; titanium oxides and kaolinite are nearly always present.
How it forms
Bauxite forms where two conditions hold for long stretches of geological time: a warm, humid climate with strong seasonal rainfall, and a stable, well-drained land surface. Under these conditions, intense chemical weathering hydrolyses silicate minerals in the parent rock, leaches silica and the alkali and alkaline-earth cations away in solution, and leaves an in-situ residue dominated by the least-soluble oxides, those of aluminium, iron, and titanium. The process operates over 10⁵–10⁷ years and requires uninterrupted tectonic stability. The world’s great bauxite plateaux, the Fouta Djallon in Guinea, the Darling Range in Western Australia, the Trombetas in Brazil, all sit on long-stable cratonic surfaces.
Because bauxite formation is so tightly tied to climate and palaeolatitude, ancient bauxite horizons are widely used as palaeoclimatic markers. Their distribution through the Phanerozoic correlates with greenhouse intervals, Carboniferous, Late Cretaceous, Paleocene–Eocene, Middle Miocene, and with continental positions in tropical latitudes.
Lateritic versus karst bauxite
Two genetic classes account for almost all known deposits.
Lateritic bauxites form on aluminosilicate parent rocks, granite, gneiss, basalt, syenite, shale, in the modern tropical and subtropical belt. They are volumetrically dominant (~88 % of global resources), produce thick blanket-like deposits, and supply nearly all of the world’s mined bauxite. Guinea, Australia, Brazil, India, Indonesia, and Vietnam host the major lateritic provinces.
Karst bauxites form in solution depressions on carbonate platforms (limestone, dolomite). They are typically older, many are Mesozoic or even Palaeozoic, and represent fossil weathering systems that have since been buried, exhumed, or tectonically deformed. The Mediterranean province (Greece, Croatia, Hungary, southern France, Turkey) is the type example, alongside Jamaica and Hispaniola.
A small third category, the Tikhvin-type (or sedimentary type), forms by reworking and redeposition of older lateritic bauxite onto an aluminosilicate substrate. The original Tikhvin deposit east of St Petersburg is the namesake.
Where it’s mined today
The latest USGS revision puts 2024 world bauxite mine production at roughly 428 million tonnes. The largest producers were Guinea, Australia, China, Brazil, India, and Indonesia.
- Guinea ~130 Mt; the Boké–Sangarédi region on the Fouta Djallon is the world’s premier export source.
- Australia ~100 Mt; Weipa on Cape York Peninsula and the Darling Range west of Perth.
- China ~93 Mt; mostly diaspore-type karst bauxite in Shanxi, Henan, Guizhou, and Guangxi.
- Brazil 33 Mt; Trombetas and Juruti in the Amazon basin.
- Indonesia 32 Mt; Bintan and West Kalimantan.
- India 25 Mt; mainly Odisha and Andhra Pradesh.
Almost all production comes from open-pit mines, since lateritic bauxite forms a near-surface blanket usually only a few metres to a few tens of metres thick.
From rock to metal
Aluminium extraction is a two-step industrial process and has been since the late nineteenth century. The Bayer process (Karl Josef Bayer, 1888) digests crushed bauxite in hot concentrated sodium hydroxide; aluminium hydroxides dissolve as sodium aluminate while iron oxides, titanium oxides, and silicate residues remain as solid waste; the so-called red mud, or bauxite residue. Pure aluminium hydroxide is then precipitated and calcined to alumina (Al₂O₃). The Hall–Héroult process (1886, independently invented by Charles Hall in the United States and Paul Héroult in France) reduces the alumina to metallic aluminium by electrolysis in a molten cryolite (Na₃AlF₆) bath. As a working ratio, roughly four tonnes of dry bauxite yield two tonnes of alumina, which yield one tonne of aluminium.
Beyond aluminium, bauxite is consumed directly in the manufacture of refractory bricks, abrasive corundum, calcium-aluminate cement, and proppants for hydraulic fracturing. Bayer refining also produces bauxite residue, better known as red mud: a highly alkaline waste dominated by iron oxides, titanium oxides, residual alumina, silica, and caustic soda. More than four billion tonnes are already stored worldwide, making it one of the aluminium industry’s largest environmental liabilities.
