cupellation

thumb|200px| 16th century cupellation furnaces (per Georgius Agricola|Agricola)

Cupellation is a refining process in metallurgy in which ores or alloyed metals are heated to very high temperatures and subjected to controlled operations to separate noble metals like gold and silver, from base metals like lead, copper, zinc, arsenic, antimony, or bismuth, in the ore. Cupellation is based on the principle that precious metals typically oxidise or react chemically at much higher temperatures than base metals. At high temperatures the precious metals remain separate but the others react, forming slags or other compounds.