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By contrast, depletion gilding is a subtractive process whereby material is removed to increase the purity of gold that is already present on an object's surface. In depletion gilding, other metals are etched away from the surface of an object composed of a gold alloy by the use of acids or salts, often in combination with heat.
Gold parting is the separating of gold from silver ... "Depletion Gilding from Third Millennium BC Ur". Iraq. 57: 41–47. doi:10.2307/4200400.
Keum-boo (Korean: 금부; also Geumbu, Kum-Boo or Kum-bu—Korean "attached gold") is an ancient Korean gilding technique used to apply thin sheets of gold to silver, to make silver-gilt. Traditionally, this technique is accomplished by first depleting a surface of sterling silver to bring up a thin layer of fine silver.
In depletion gilding, a subtractive process discovered in pre-Columbian Mesoamerica, articles are fabricated by various techniques from an alloy of copper and gold, named tumbaga by the Spaniards. The surface is etched with acids, resulting in a surface of porous gold.
The gold Muisca raft in the Museo del Oro, Bogotá. Metallurgy gradually spread north into Colombia, Panama and Costa Rica, reaching Guatemala and Belize by 800 CE. By c. 100–700 CE, depletion gilding was developed by the Nahuange culture of Colombia to produce ornamental variations such as rose gold. [20]
The 'white gold' rush: Why lithium demand is skyrocketing and what it means for consumers. ... In some areas extraction has been linked to water depletion and other issues.
The gold mine, Yanacocha, is a massive operation, sprawling across hundreds of square miles at elevations as high as 13,000 feet. The International Finance Corp., part of the World Bank Group, provided loans to help build and expand the mine and owns a small stake in it. Since 1993, Yanacocha has yielded more than 35 million ounces of gold.
A distinctive depletion gilding technique was developed by the Incas in Pre-Columbian South America. "Overlaying" or folding or hammering on gold foil or gold leaf is mentioned in Homer's Odyssey (Bk vi, 232). [2] Fire-gilding with mercury dates to at least the 4th century BC, and was the most common method until the Early Modern period at least.