Gold is chemically quite inert. No single acid dissolves it. It is unaffected by oxygen or hydrogen sulfide. Gold does not rust, tarnish, corrode, crumble, decompose or decay, even after centuries on the sea floor or in a damp dripping cavern. Electrum is the usual name applied to gold containing a high silver content.
Gold sometimes occurs in nature in combination with tellurium in the mineral sylvanite.
Gold chlorides and cyanides also occur more rarely. Gold is number 81 down on a list of the atomic elements in terms of relative abundance in the universe and has been highly prized for jewelry and coins since the dawn of mankind. The famous gold mines of South Africa are more than a mile deep. Gold is often recovered as a by-product of other metal mining, for example copper or lead. The total amount of gold mined in the world in the history of mankind amounts to less than 90,000 tons.