Patio process (silver amalgamation)

What it is

Ground silver ore mixed with mercury, salt and copper sulphate on large patios, where the mercury amalgamates the silver in the cold. It made it possible to work poor-grade ores and multiplied American silver production.

Medina was from Seville, but the method was developed in New Spain; it was adopted in Potosí in 1572.

What it led to

• the boom of Zacatecas and Potosí
• the flow of silver that monetised the world economy and China
• demand for mercury from Almadén and Huancavelica

Built on

• Mercuryc. 1500 BCE
• Huayrachina wind-driven smelting furnacec. 1450

Made possible

• Huancavelica mercury mine1563
• Potosí hydraulic system and ingenios1573-1621

Links