In the extraction of Silver and Gold, NaCN is used to leach the metal. 4‌Au(s)+8CN(aq)+2H2O+O2(g) ‌‌→4[Au(CN)2]−(aq)+4OH−(aq) 2[Au(CN)2]−(aq)+Zn→2‌Au(s)+[(Zn(CN)4)]2−(aq) In case of ore containing ZnS and PbS, the depressant used is NaCN.