Mercury has a long history of being used for amalgamation of native gold in placer type operations. The process is one of simple dissolution, where a pan is used to produce a heavy mineral concentrate which might be enriched in native gold. The mercury is swirled around the concentrate and will dissolve the gold into an amalgam. This amalgam can then be separated through gravity and heated to evaporate the mercury, leaving behind gold. In some cases it was used as a gold test to validate the presence of fine grained gold on a prospect. In others it was the main method of gold processing. Mercury would get released in the site through spillage and through evaporation.

It is not a process I have seen in use personally in any of the mining operations I have visited or worked at. It is still used today by garrimperos and other artisanal gold panners. (here is an example of how it is done)