I did not know you could dissolve gold in mercury, pretty cool. After a little research, I found out that the process can also be reversed (obviously, since it's used for gold extraction), like it was with aqua regia to recover the dissolved medals' gold, by simply evaporating the mercury (since it's boiling point is much lower than gold's):

http://en.wikipedia.org/wiki/Amalgam_(chemistry)#Gold_extrac...

http://nevada-outback-gems.com/Reference_pages/Amalgamation....

This however, has to be done in a controlled manner due to the toxicity of mercury, which is also why mercury apparently isn't commonly used to extract gold anymore.