How was mercury used in gold and silver amalgamation?

Amalgamation is a process used to recover fine particulate gold and silver by exploiting their solubility in mercury. When these metals contact a fresh mercury surface, they are wetted and dissolved to form an amalgam, a crystalline or liquid alloy.12

The process is typically performed using one of several methods:
* Surface contact: Passing a slurry of ore over mercury-coated copper plates.1
* Vessel mixing: Agitating a slurry of ore and mercury in a cylindrical or conical vessel known as an amalgam barrel.1
* Milling: Adding mercury to a ball, rod, or pebble mill during the grinding of ore to dissolve the liberated gold or silver.12

Once the denser amalgam is separated from the barren ore, it is washed and filtered to remove impurities. Finally, the mixture is heated in a sealed retort to distill off the mercury, which is recovered for reuse, leaving the precious metal as a residue. Due to the severe risks of mercury poisoning to operators and the environment, this practice requires strictly controlled equipment and safety protocols.123