Tumbaga

Composition and properties

• Tumbaga is an alloy of gold and copper.
• It has a lower melting point than gold or copper alone.
• Tumbaga is harder than copper but remains malleable.
• It can be treated with citric acid to dissolve copper, leaving a layer of pure gold.
• This process is called depletion gilding.

Use and function

• Pre-Columbian cultures used tumbaga to make religious objects.
• Tumbaga is versatile and can be cast, drawn, hammered, gilded, etc.
• The proportion of gold to copper in artifacts varies widely.
• Some tumbaga also contains other metals, up to 18% of the total mass.
• Lost wax technique and depletion gilding were commonly used to make tumbaga objects.

The Tumbaga Wreck

• In 1992, silver tumbaga bars were found in wreckage off Grand Bahama Island.
• The bars were made from plundered silver, copper, and gold.
• They were melted into tumbaga bars for transport.
• Tumbaga bars were usually melted back into their constituent metals in Spain.

Related alloys

• Guanín: Pre-Columbian Central American alloy.
• Tombac: Copper-zinc alloy.
• Orichalcum: Fabulous metal mentioned in ancient writings.
• These alloys are related to tumbaga.

References

• Tumbaga definition in Wiktionary.
• Fester, G. A. (1962). Copper and Copper Alloys in Ancient Argentina.
• Chymia. 8: 21–31. doi:10.2307/27757215.
• The Tumbaga Saga: Treasure of the Conquistadors by Daniel Frank Sedwick.
• Additional references can be found in the Wikipedia article on Tumbaga.

Tumbaga Data Sources