Potosí Mercury Amalgamation Silver Process

Type Object Region Peru Time c. 1630–1640

In the 1630s the Potosí silver mines used the patio amalgamation process on a large scale to refine low-grade silver ores, combining mita forced labo…

Timeline

1635Potosí · PotosíIn the 1630s Potosí widely adopted the patio process: crushed silver ore, salt, copper sulfate, and mercury were trodden together on open patios to form an amalgam, which was then distilled to recover mercury and refine crude silver, well suited to processing the low-grade ores of Cerro Rico.
c. 1632–1639Potosí · PotosíNumerous water-powered arrastras and trapiches ground the ore to the proper particle size, while mercury came mainly from the Huancavelica mine in Peru; the colonial authorities established controls on the mercury-to-silver ratio to maintain refining efficiency and royal revenue.
c. 1635–1640Lima (silver transshipment hub) · LimaIn the 1630s Potosí's silver production accounted for a significant share of the global total, flowing into China and Europe via the Manila galleons and transatlantic routes, making amalgamation a core industrial technology of the early globalized precious-metal network.

Sources

Potosí: The Silver City That Changed the World — Kris Lane (2019)
The Cambridge Economic History of Latin America, Volume 1 — Victor Bulmer-Thomas; John Coatsworth; Roberto Cortés Conde (eds.) (2006)