A 3000-year-old rectangular copper mask found in Argentina is one of the oldest human-made metal object from South America.

Archeologists say the discovery goes against the idea that South American metal work originated in Peru.

The mask, found in the same place where adults and children were buried, has holes in its eyes, nose and mouth positions - with small openings on the side that could have been used with thread to attach the mask to a face.

Front (A) and back (B) view of the 3,000 year-old copper mark. Some of the small, circular perforations near the edges, which could have been used with thread to attach the mask to a face, are visible

The mask was discovered in the southern Andes in Argentina, at an archaeological site called Bordo Marcial.

Metallurgy in pre-Colombian America first developed in the Andes, and Peru has long been considered to be the initial point of origin - but the recent discovery of the copper mask in north-west Argentina points to the southern Andes a a center of early metalworking.

The excavation of the site where the mask was found revealed a collective burial of at least 14 people.

The mask was discovered in the southern Andes in Argentina, at an archaeological site called Bordo Marcial

The mask is about 18 centimeters (7 inches) long and 15 centimeters (5.9 inches) wide, and 1 millimeter (0.04 inches) thick.

It's perforated near the left eye, and the entire mask is fractured and covered by a layer of corrosion from natural weathering.

To preserve the mask and prevent further damage, the researchers didn't remove this layer of corrosion.

Copper ore was found within 44 miles (70 kilometers) of the the site, suggesting that the mask was made locally.

To make the mask, the researchers said that someone would have hammered the metal while it was cold, and then reheated it.

Pictured is the Bordo Marcial tomb where the mask was found (circled in dotted lines). The site revealed a collective burial of at least 14 people, including adults and children

Based on this evidence, the researchers, based at the University of Bueno Aires, say that metalworking in Argentina emerged at the same time as in Peru.

Gold objects estimated to be 4,000 years old have been found in southern Peru, according to a February 2008 study, and bronze objects dating from AD 1,000 have also been found in the Peruvian Andes - however, experts weren't sure if the objects originated there or if they were brought there.

A copper pendant was found buried with a child's remains in a site nearby to the mask

The mask, as well as the human remains, were exposed to rain from the summer rainy season.

The bones were mixed together, with the mask on top of a corner on the pile.

Near the site, a second burial site was found, containing the remains of an eight to 12-year-old - dating from 3,000 years ago as well.

The child was buried with a stone bead and a copper pendant, with a small hole near the top.

'Proof of copper smelting and annealing further highlights the northwest Argentinian valleys and northern Chile as early centers in the production of copper,' the researchers wrote.

'This data is essential to any narrative that seeks to understand the emergence of Andean metallurgy,' they wrote.