Page "Gold" Paragraph 2

Gold resists attacks by individual acids, but it can be dissolved by the aqua regia ( nitro-hydrochloric acid ), so named because it dissolves gold.

Gold also dissolves in alkaline solutions of cyanide, which have been used in mining.

Gold dissolves in mercury, forming amalgam alloys.

Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to confirm the presence of gold in items, giving rise to the term the acid test.