Potassium cyanide or KCN is the salt of potassium and hydrogen cyanide. It is a colorless compound with smell of almonds, similar in appearance to sugar and highly soluble in water. Despite being highly toxic, it is one of the few substances that form soluble compounds with gold, and thus is used in jewellery for chemical gilding and buffing. It is also sometimes used in gold mining for chemical extraction of metal from ore (though sodium cyanide is more commonly used). ...