As one of the coinage metals, it 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.
The metal occurs as nuggets or grains in rocks, in veins and in alluvial deposits. Figures as at 2011, record a total of 166,600 tonnes of gold that have been mined in human history.
Modern industrial uses include dentistry and electronics, where gold has traditionally found use because of its good resistance to oxidative corrosion and excellent quality as a conductor of electricity.
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.
Chemically, gold is a transition metal and can form trivalent and univalent cations in solutions. Compared with other metals, pure gold is more chemically unreactive, but it is attacked by aqua regia (a mixture of acids), forming chloroauric acid, and by alkaline solutions of cyanide but not by single acids such as hydrochloric, nitric or sulfuric acids. Gold dissolves in mercury, forming amalgam alloys, but does not react with it.
It 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.
Source: World Gold Council (www.gold.org)