Aqua regia

Aqua regia  (Latin: royal water)

Aqua regia is a higly corrosive, fuming yellow or red solution. It is a mixture of (usually) 1 part nitric acid (HNO3) to three parts hydrochloric acid (HCl). It is one of the few reagents that can dissolve gold and platinum.

Aqua regia is itself very corrosive and has been implicated in several explosions as well due to mishandling and it should not be used unless gentler cleaning techniques are inadequate.

Due to the reaction between its components resulting in its decomposition, aqua regia quickly loses its effectiveness. As such, its components should only be mixed immediately before use.