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 at room temperature, although gallium and cesium are liquid on hot days (bromine is also a liquid, but it is non-metallic). Mercury 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 has been 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. The use of mercury in products has been greatly reduced over time due to its toxicity. Mercury is very poisonous as 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.”  As the use of mercury has decreased, the mercury in old products is increasingly recycled for any continued uses.

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 and occurs in the mineral cinnabar (mercury sulfide). With the decline of the use of mercury in many products, mining for mercury as a primary product has greatly reduced over time.