Metallurgy in pre-Columbian America is the extraction, purification and alloying of metals and metal crafting by Indigenous peoples of the Americas prior to European contact in the late 15th century. Indigenous Americans had been using native metals from ancient times, with gold artifacts from the Andean region being dated to 2155–1936 BC, and North American copper artifacts being dated to approximately 5000 BC. The metal would have been found in nature without the need for smelting, and shaped into the desired form using hot and cold hammering without significant chemical changes or alloy formation. As of 1999, "no one has found evidence that points to the use of melting, smelting and casting in prehistoric eastern North America." In South America the case is quite different. Indigenous South Americans had full metallurgy with smelting and various metals being purposely alloyed. Metallurgy in Mesoamerica and western Mexico may have developed following contact with South America through Ecuadorian marine traders.
South America
South American metal working seems to have developed in the Andean region of modern Peru, Bolivia, Ecuador, Chile, and Argentina with gold and copper being hammered and shaped into intricate objects, particularly ornaments. Recent finds date the earliest gold work to 2155–1936 BC. and the earliest copper work to 1432–1132 BC. Ice core studies in Bolivia suggest copper smelting may have begun as early as 700 BC, over 2700 years ago. By 1410–1090 BC, gilding was practiced in coastal Peru. Further evidence for this type of metal work comes from the sites at Waywaka (near Andahuaylas in southern Peru), Chavín and Kotosh, and it seems to have been spread throughout Andean societies by the Early horizon (1000–200 BC). Unlike other metallurgy traditions where metals gained importance through practical use in weaponry and everyday utensils, metals in South America (and later Central America) were mainly valued as adornments and status objects. Though also functional objects were produced, even in the metallurgically advanced Andean cultures of the Inca era stone tools were never completely replaced by bronze items in everyday life. During the Early horizon, advances in metal working produced spectacular and characteristic Andean gold objects made by the joining of smaller metal sheets, and also gold-silver alloy appeared. Two traditions seem to have developed alongside each other – one in northern Peru and Ecuador, and another in the Altiplano region of southern Peru, Bolivia and Chile. There is evidence for smelting of copper sulphide in the Altiplano region around the Early horizon. Evidence for this comes from copper slag recovered at several sites, with the ore itself possibly coming from the south Chilean-Bolivian border. Near Puma Punku, Bolivia, and at three additional sites in Peru and Bolivia, portable smelting kilns were used to cast I-shaped "cramps" (fasteners) in place, to join large stone blocks during construction. Their chemical analysis shows
The estimated date of these pours lies between 800 and 500 BC. Evidence for fully developed smelting, however, only appears with the Moche culture (northern coast, 200 BC – 600 CE). The ores were extracted from shallow deposits in the Andean foothills. They were probably smelted nearby, as pictorially depicted on the metal artifacts themselves and on ceramic vessels. Smelting was done in adobe brick furnaces with at least three blow pipes to provide the air flow needed to reach the high temperatures. The resulting ingots would then have been moved to coastal centers for shaping in specialised workshops. Two workshops studied were near the administrative sections of their towns, again showing the prestige of metal. Analysis of a Moche statue composed of numerous thin metal layers revealed complex plating and gilding involving a combination of immersion in acidic solutions and the application of extreme heat. The objects themselves were still mainly adornments, now often being attached to beads. In fact, in the Lambayeque and Chimu cultures (750–1400 CE), a wide range of functional metal items were produced such as bowls, plates, drinking vessels, boxes, models, scales and especially beakers (acquillas), but mostly for ceremonial or elite use. Some functional objects were fashioned, but they were elaborately decorated and often found in high-status burials, seemingly still used more for symbolic than for practical purposes. The appearance of gold or silver seems to have been important, with a high number of gilded or silvered objects as well as the appearance of Tumbaga, an alloy of copper and gold, and sometimes also silver. Arsenic bronze was also smelted from sulphidic ores, a practice either independently developed or learned from the southern tradition. The earliest known powder metallurgy, and earliest working of platinum in the world, was apparently developed by the cultures of Esmeraldas (northwest Ecuador) before the Spanish conquest Beginning with the La Tolita culture (600 BC – 200 CE), Ecuadorian cultures mastered the soldering of platinum grains through alloying with copper, gold and silver, producing platinum-surfaced rings, handles, ornaments and utensils. This technology was eventually noticed and adopted by the Spanish c. 1730. Coastal communities in the Atacama Desert, as exemplified by those near Tocopilla, produced their own metal objects for practical use in the 900–1400 CE period.
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. Muisca goldworking, from modern Colombia, made a wide variety of small ornamental and religious objects from about 600 CE onwards. The gold Muisca raft is probably the best-known single object. This is in the Gold Museum, Bogotá, the largest of the six "gold museums" owned by the Central Bank of Colombia displaying gold from the Muisca and other pre-Columbian cultures in the country. Many copper objects produced in the Tiwanaku polity (c. 600–c. 1000) are alloys that are characterized by having approximately 5% arsenic and 4% nickel.
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