Which metal is extracted from the ore bauxite?

Aluminium, the most abundant metal in the crust - and for most of the nineteenth century it was more valuable than gold, because separating it from oxygen is extremely difficult. Napoleon III reportedly reserved aluminium cutlery for his most honoured guests, with the rest making do with gold, and the Washington Monument was capped with a small aluminium pyramid as a display of wealth.

Two men solved it independently in the same year, 1886, at the same age of 22 - Charles Hall in America and Paul Héroult in France - by dissolving alumina in molten cryolite and running an electric current through it. The price collapsed by a factor of hundreds within a few years, and a precious metal became foil.

The process is enormously electricity-hungry, which is why smelters are built next to hydroelectric dams and why aluminium is sometimes described as solid electricity. Recycling it uses about five per cent of the energy of making it new, which makes aluminium cans one of the few recycling propositions that is unambiguously worth it economically as well as environmentally.