Gold is a chemical element with the symbol : aurum) and atomic number 79, making it one of the higher atomic number elements that occur naturally. In a pure form, it is a bright , slightly reddish yellow, dense, soft, malleable metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in free elemental (native) form, as nuggets or grains, in rocks, and in alluvial deposits series with the native element silver), naturally alloyed and palladium such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides ).
Gold is resistant to most acids , though it does dissolve in aqua regia and hydrochloric acid ), which forms a soluble tetrachloroaurate. Gold is insoluble in nitric acid, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test solutions of cyanide and electroplating. Gold dissolves in mercury alloys, but this is not a chemical reaction.
A relatively rare element, gold is a precious metal , jewelry throughout recorded history was often implemented as a monetary policy , but gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a fiat currency system after 1971.
A total of 197,576 tonnes of gold exists above ground, as of 2019 This is equal to a cube with each side measuring roughly 21.7 metres. The world consumption of new gold produced is about 50% in jewelry, 40% in investments Gold's high malleability, ductility, resistance to corrosion and most other chemical reactions, and conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices (its chief industrial use). Gold is also used in infrared production, gold leafing. Certain gold salts are still used as anti-inflammatories , the world's largest gold producer by far was China