Gold is a chemical element with the symbol Au (from Latin: aurum, "shining
dawn") and an atomic number of 79. It has been a highly sought-after precious
metal for coinage, jewelry, and other arts since the beginning of recorded
history. The metal occurs as nuggets or grains in rocks, in veins and in
alluvial deposits. Gold is dense, soft, shiny and the most malleable and ductile
pure metal known. Pure gold has a bright yellow color and luster traditionally
considered attractive, which it maintains without oxidizing in air or water.
Gold is one of the coinage metals and has served as a symbol of wealth and a
store of value throughout history. Gold standards have provided a basis for
monetary policies. It also has been linked to a variety of symbolisms and
ideologies.
A total of 161,000 tonnes of gold have been mined in human history, as of
2009.[1] This is roughly equivalent to 5.175 billion troy ounces or, in terms of
volume, about 8,333 cubic meters.
Although primarily used as a store of value, gold has many modern industrial
uses including dentistry and electronics. Gold has traditionally found use
because of its good resistance to oxidative corrosion and excellent quality as a
conductor of electricity.
Chemically,
gold
rings is a transition metal and can form trivalent and univalent cations in
solutions. Compared with other metals, pure gold is chemically least reactive,
but it is attacked by aqua regia (a mixture of acids), forming chloroauric acid,
but not by the individual acids, and by alkaline solutions of cyanide. Gold
dissolves in mercury, forming amalgam alloys, but does not react with it. Gold
is insoluble in nitric acid, which dissolves silver and base metals. This
property is exploited in the gold refining technique known as "inquartation and
parting". Nitric acid has long been used to confirm the presence of gold in
items, and this is the origin of the colloquial term "acid test", referring to a
gold standard test for genuine value.
From Wikipedia http://en.wikipedia.org/wiki/Gold