What process is used to separate gold atoms from crushed rock?

Mercury is most often used. Elemental mercury is combines with the crushed and powdered rock to form a slurry and create a gold amalgam. This amalgam needs to be separated from the mercury and crushed rocks through a fine seize or chamois leather, letting the mercury come through but the amalgam to stay behind. The amalgam is now heated, letting the mercury to sublime from the amalgam leaving behind elemental gold in the mixture.