Gold (IPA: /'g??ld/) is a highly sought-after precious metal that for many centuries has been used as money, a store of value and in jewellery. The metal occurs as nuggets or grains in rocks and in alluvial deposits and is one of the coinage metals. It is a soft, shiny, yellow, dense, malleable, and ductile (trivalent and univalent) transition metal. Modern industrial uses include dentistry and electronics. Gold forms the basis for a monetary standard used by the International Monetary Fund (IMF) and the Bank for International Settlements (BIS). Its ISO currency code is XAU. Gold is a chemical element in the periodic table with the symbol Au (from the Latin aurum) and atomic number 79. The adjective auric refers to something made of gold. Gold does not react with most chemicals but is attacked by chlorine, fluorine, aqua regia and cyanide. Gold dissolves in mercury. In particular, gold is insoluble in nitric acid, which will dissolve most other metals. Nitric acid has long been used to confirm the presence of gold in items.