A historic metallurgical technique where crushed gold or silver ore is placed into a rotating wooden or steel drum along with a solvent like mercury, chlorine, or cyanide. The tumbling action provides continuous agitation, maximizing contact between the precious metal particles and the reagent to ensure efficient extraction before the slurry is washed and processed.
Heard on the job
The old mill ruins still have the concrete mounts where the barrel process was used to amalgamate the silver.