Native silver metal forms a water soluble complex with a dilute aqueous solution of $\mathrm{NaCN}$ in the presence of

A water soluble complex of silver with a dilute aqueous solution of $\mathrm{NaCN}$ is sodium argentocyanide. In the cyanide process, the native form is crushed and treated with $0.1-0.2 \%$ solution of $\mathrm{NaCN}$ and aerated. $$ 4 \mathrm{Ag}+8 \mathrm{NaCN}+2 \mathrm{H}_2 \mathrm{O}+\mathrm{O}_2 \longrightarrow 4 \mathrm{Na}\left[\mathrm{Ag}(\mathrm{CN})_2\right]+4 \mathrm{NaOH} $$ Argentocyanide is soluble. Further, metals are recovered from the complex by reduction with zinc