The arc furnace

Silicon starts its life in a furnace hotter than lava, where quartz meets coal. Three carbon electrodes plunge into a vessel filled with quartz, coal and wood chips, and an electric arc heats the mix to over 1,800 °C1. At that heat, carbon tears the oxygen away from the quartz and liquid silicon is left, tapped and broken into lumps. This is called metallurgical silicon: pure to within a few percent, still very far from a chip. The world makes about 4.6 Mt2 of it a year, 80%3 of it in China, mostly for aluminium and silicones. Norway, with its dam-powered electricity, remains one of the West's main suppliers.