Aqueous sodium cyanide is used as a reagent in the extraction of some metals. This process is called

• Pyrometallurgy uses heat for reduction of metals
• Electrometallurgy uses electricity for reduction of metals
• Hydrometallurgy uses water medium in soluble complex form for metal reduction.

Silver and gold are extracted by a method involving complex formation.
Powdered argentite is reacted with a dilute solution of sodium cyanide in the presence of air. The silver from the ore is dissolved in the cyanide solution forming sodium argentocyanide.