80Hg Mercury

Year Discovered


Discovered By


Biological Rating

Not necessary for life.


Named for the planet Mercury, it is a shiny, silvery, liquid metal, traditionally called “quick silver”. It is the only liquid metal, although gallium and cesium are liquid on hot days (bromine is also a liquid, but it is non-metallic). It has been known to humans for at least 4,000 years. Mercury is a stable metal, not reacting with air, water, most acids and most bases. It is a poor conductor of heat (for a metal) but a good conductor of electricity. Alloys of mercury with other metals are called amalgams. Mercury’s ability to amalgamate with many metals is often useful in purifying the other metal, especially gold. Mercury is used for street lights, advertising lights, fungicides, pesticides, dental preparations, batteries, caustic soda and chlorine production, catalysts, electrical equipment and silent electrical switches. It is also used where a heavy liquid is needed, such as barometers or thermometers. Mercury is very poisonous, it damages the central nervous system. It is absorbed easily by the body, but cannot be excreted easily. Mercury is volatile and it is possible to breath mercury vapors without ever touching the metal. Mercury must be handled with adequate protection. The symbol for mercury, Hg, comes from mercury’s Latin name hydrargyrum, which means “liquid silver”.

Biological Benefits

Mercury has no known biological use. However, it is widespread through the biosphere and the food chain.

Role in Life Processes

No known benefit for life processes in plants and animals.

Percentage Amount in the Human Body: 0.000009%


Pure mercury is found in volcanic rocks, but mercury usually occurs in the mineral cinnabar (mercury sulfide). Cinnabar is mined in Russia, Mexico, Spain and Algeria.