The process of concentrating Au and Ag ores is based upon their solubility in :

The separation of Ag and Au from their respective ores is done by using the cyanide method or commonly known as Mac Arthur Forrest Process. This method or process is based on the principle that Ag and Au dissolved in KCN to form a cyanide complex. Then when this cyanide complex is treated with Zinc, Ag is successfully extracted.

$\begin{array}{ccc}{\mathrm{Ag}}_2\mathrm{S}+4\mathrm{KCN}& \to & 2\mathrm{K}\left[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2\right]+{\mathrm{K}}_2\mathrm{S}\\ 2\mathrm{K}\left[\mathrm{Ag}{\left(\mathrm{CN}\right)}_2\right]+\mathrm{Zn}& \to & {\mathrm{K}}_2\left[\mathrm{Zn}{\left(\mathrm{CN}\right)}_4\right]+\mathrm{Ag}\end{array}$