A publication of the Archaeological Institute of America
Discovery of small pieces of copper and gold foil at Mina Perdida, south of Lima, Peru, has pushed back the date of the earliest metalworking in the Andes to at least 1100 B.C. and shed light on the origins of the spectacular metalwork of the Chavín (900-200 B.C.) and Moche (A.D. 50-800) cultures.
Excavations directed by Yale University archaeologists Richard L. Burger and Lucy Salazar-Burger have revealed a flat-topped 72-foot-high pyramid and two lower platform mounds in a U-shaped configuration around a plaza, as well as residential areas. The foil fragments were found on one platform mound, the pyramid's summit, and a terrace immediately behind the pyramid, but not in the residential areas. Radiocarbon dates of materials associated with the copper are between ca. 1500 and 1100 B.C.
Analyses by Robert Gordon of Yale's department of geology and geophysics showed the copper to be 99.5 percent pure. The presence of arsenic and silver (commonly found in native copper) and absence of iron (present in higher concentrations in smelted coppers) suggests the Mina Perdida metal is native copper. Small veins of gold and copper do crop out along the coast of central Peru. Elongated grains indicate that the metal was hammered into foil while cold. The artifacts suggest that an early metalworking stage, employing naturally occurring metals, was the basis for later developments in the region.