 Occurrence
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| In 2005, China was the top producer of mercury with almost two-thirds global share followed by Kyrgyzstan, reports the British Geological
Survey. Several other countries are believed to have unrecorded production of mercury from copper electrowinning processes
and by recovery from effluents.
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| Mercury is an extremely rare element in the earth's crust, having an average crustal abundance by mass of only 0.08 parts
per million. However, because it does not blend geochemically with those elements that comprise the majority of the crustal
mass, mercury ores can be extraordinarily concentrated considering the element's abundance in ordinary rock. The richest mercury
ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times
average crustal abundance).
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| It is found either as a native metal (rare) or in cinnabar (HgS), corderoite, livingstonite and other minerals, with cinnabar
(HgS) being the most common ore. Mercury ores usually occur in very young orogenic belts where rock of high density are forced
to the crust of the Earth, often in hot springs or other volcanic regions.
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| Over 100,000 tons of mercury were mined from the region of Huancavelica, Peru, over the course of three centuries following the discovery of deposits there in 1563; mercury from Huancavelica was crucial
in the production of silver in colonial Spanish America. Many former ores in Italy, Slovenia, the United States and Mexico which once produced a large proportion of the world's supply have now been completely mined out. The metal is extracted by
heating cinnabar in a current of air and condensing the vapour. The equation for this extraction is;
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HgS + O2  Hg + SO2 |
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