Tumbaga

What remains is a shiny layer of nearly pure gold on top of a harder, more durable copper-gold alloy sheet.

Tumbaga was widely used by the pre-Columbian cultures of Central and South America to make religious objects, as they considered gold a sacred metal.

Like most gold alloys, tumbaga was versatile and could be cast, drawn, hammered, gilded, soldered, welded, plated, hardened, annealed, polished, engraved, embossed, and inlaid.

[clarification needed] The object was placed in an oxidizing solution, likely composed of sodium chloride (salt) and ferric sulfate.

They were composed mainly of silver, copper, and gold plundered by the Spaniards during the conquests of Cortés and hastily melted into bars of tumbaga for transport across the Atlantic.