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What is Mercury?
Mercury is a metal and one of the basic elements that makes-up the Earth’s composition
where it is generally found associated with sulfur under the form of cinnabar ore (or
mercury sulfide). It is a relatively scarce element, making up less than one one-millionth
of the Earth’s crust. It is extracted from its mineral form by heating cinnabar in a current
of air and by condensing the vapor. Once isolated in its pure metallic form, mercury
exhibits the unique property of being liquid at room temperature. As with any element,
mercury cannot be created or destroyed. Mercury is known as a “heavy metal,” because
it is very dense; meaning a small amount is very heavy. A cup of liquid mercury, for
example, weighs about thirteen times more than a cup of water.
Mercury exists in many forms in the environment. It is present in the atmosphere mainly
as a metallic vapor; it forms different chemical compounds such as salts in water and soil;
and it occurs in organic forms, found mainly in living organisms.
Mercury has a number of other unusual properties. In its pure liquid form, it becomes
highly volatile. It conducts electricity and expands or contract evenly in response to
changes in pressure or temperature. Mercury combines easily with most metals, forming
metal alloys such as dental filling amalgam. In its vapor form, it can also combine with a
variety of gaseous elements, yielding molecules that can emit light under the stress of
electricity. These properties have made mercury a widely used product in household,
commercial, medical and industrial applications. The metal alloys forming capability of
mercury also brought its widespread us in gold mining activities. Mercury, in various
forms, is also one of the most poisonous natural substances known to humans and most
other forms of life, making it an effective pesticide, fungicide and preservative. It is this
poisonous property that has drawn international attention to mercury in the environment
and led many countries to begin the phase-out of most uses.