Gold+mining

Potassuim Cyanide Potassium Cyanide is a white crystal solid that resembles sugar. It is highly toxic to humans. Potassium Cyanide is used in gold mining as a process called __Gold cyanidation__. When the Potassium Cyanide makes contact with gold ores the gold becomes liquefied and is then removed. 

Sources:

http://www.answers.com/topic/potassium-cyanide