Around 1500 tons of gold are produced around the world every year. Most of this gold comes from South Africa. Two methods are used to extract gold from the rocks where it is found. Gold can be extracted using mercury. The minerals containing gold are mixed with mercury. The gold will dissolve in the mercury to form an amalgam or alloy of mercury. The amalgam is then filtered and heated so that the mercury evaporates, leaving pure gold behind. In another popular method, the minerals containing gold are added to a sodium cyanide solution.
This solution reacts with the gold to form a new compound. The solution is then filtered to remove impurities. Later, zinc is added to the solution which reacts with the compound to produce pure gold.
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