patio process

patio process

Method of isolating silver from its ore, apparently dating from pre-Columbian times. The ore was crushed and ground by mule power in arrastras, reducing it to a fine mud. This was then spread over a courtyard or patio, sprinkled with mercury, salt, and copper sulfate, and mixed by driving mules over it. Chemical reactions caused the silver to dissolve in the mercury. When the amalgamation was complete, the material was agitated with water in large tubs and the mud run off. The amalgam at the bottom was collected and heated to drive off the mercury. Used for much of the world's silver production for 350 years, the process was replaced by the cyanide process early in the 20th century.


patio process or Mexican process

This entry comes from Encyclopædia Britannica Concise.
For the full entry on patio process, visit

Seen & Heard

What made you look up patio process? Please tell us what you were reading, watching or discussing that led you here.