A small, ancient, and rectangular copper mask was found in the southern Andes in Argentina, and dated to be about 3,000 years old. According to archaeologists, it has been determined to be amongst the oldest human made objects from South America, challenging the consensus that metalworking started in Peru.
     The mask has been dated to about 1,000 BCE and was found in an area commonly associated with the burial of women and children. The mask is marked with holes for the eye and mouth, as well as openings for attaching the mask.
     A local copper ore source lies within 44 miles (70 kilometres) of where the mask was uncovered, suggesting a local production. This makes it likely that metal production in Peru was contemporary with the production in Argentina.
     Other metal objects found in South America have been discovered in souther Peru and estimated to be nearly 4,000 years old. Bronze objects dated to 1,000 CE have also been discovered in the Peruvian Andes, though determining the origin of the finds has been difficult.
     The mask was uncovered due to a summer rainy season, which also uncovered a collection of human bones in a tomb near the La Quebrada village in Northwestern Argentina. The total amount of bodies is estimated to about 14 with the bones being mixed and the mask lying in one corner.
     The mask measures about 7 inches long and 6 inches wide (18 centimetres x 15 centimetres). It is at least 99% pure copper and would have been cold hammered and then reheated. Due to the mask's shape and the age of the object, it strongly suggests a much older metal production than previously thought.
     "Proof of copper smelting and annealing [a process of cooling metal slowly to make it stronger] further highlights the northwest Argentinian valleys and northern Chile as early centers in the production of copper," the researchers wrote, adding that "This data is essential to any narrative that seeks to understand the emergence of Andean metallurgy."

Edited from LiveScience (6 June 2017)