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Zinc comes from natural mineral deposits of ore in the earth s crust. The deposits may be close to the surface, in which case they will be mined from an open pit. Alternatively, they may be some distance underground and cannot be mined directly from the surface.
Most tin is produced from an ore (raw rocky mineral) called cassiterite, which is turned into tin by smelting. First, the ore is crushed to a powder and washed free of impurities before being heated with carbon (in the form of coal) and limestone in a giant furnace. Other metals, such as iron, copper and zinc, separate out. Molten tin sinks to the bottom of the furnace and is shaped into solid blocks known as ingots.