The Geology of Aluminium: It Is Bauxite, Not Ore in the Usual Sense
Aluminium never occurs as a metal in nature. It comes from bauxite, a tropical weathering product, through specific chemical extraction, not metal mining.
Aluminium is the most abundant metal in the earth’s crust, and yet it was essentially unknown as a usable metal until the late nineteenth century, because it never occurs as a free metal. It is locked into oxide and silicate minerals everywhere, and getting it out requires both the right source rock and a genuinely energy-intensive process.
Bauxite: a weathering product, not a primary ore
Bauxite forms through the same kind of intense tropical weathering that concentrates nickel and cobalt in laterite deposits, covered on nickel’s geology page: aluminosilicate source rocks break down under heavy rainfall and heat, silica and other soluble elements leach away, and aluminium hydroxide minerals (gibbsite, boehmite, diaspore) accumulate in the residual soil. This is why the world’s major bauxite deposits, Australia, Guinea, Brazil, sit specifically in tropical and subtropical belts, the geography is a direct consequence of climate, not chance.
Why smelting location does not follow bauxite location
Turning bauxite into alumina (aluminium oxide) and then into metal is covered on this material’s mining page, and the defining input for the final, most energy-intensive step is electricity, not ore proximity. That is exactly why Iceland, Norway, and Bahrain, none of them meaningful bauxite producers, appear as smelting locations on the map above: they have cheap geothermal, hydro, or gas power, and aluminium smelters go where electricity is cheap, not where the rock is.
Sources: bauxite formation and smelting geography draw on standard economic geology and industry references (USGS Mineral Commodity Summaries, International Aluminium Institute); production figures reference the production data elsewhere on this site.