May 20, 2011 at 3:34 PM ET
Archaeologists have discovered a 12,000 year old iron-oxide mine along the coast of northern Chile that they say is the oldest evidence of organized mining found in the Americas.
The mine — essentially a 130-foot long and 20-foot wide trench — was found near Taltal by a team of researchers led by Diego Salazar from Universidad de Chile.
It was dug by the Huentelauquen people, a hunter-gatherer fisher group who were the first settlers of the region.
The iron oxide was used as a pigment primarily for symbolic purposes, the team reports in the June issue of Current Anthropology.
Remains indicate the pigment was used to paint stone and bone instruments. It was likely used in clothing and body paint as well, the researchers note.
While these uses of the pigment are widely known, the history of how indigenous groups exploited and processed the minerals is poorly understood.
The new find sheds light on the techniques and technologies to mine it, including the recovery of nearly 500 hammerstones that date back to the earliest use of the mine.
An estimated 25,000 cubic feet and 2,000 tons of rock were excavated from the mine from around 12,000 years ago to 10,500 years ago and again around 4,300 years ago, according to radio carbon dates from charcoal and shells found in the mine.
The earliest stages of production of the mine are contemporary with the oldest human occupations in northern Chile, the researchers note, and extends by several thousand years the record of mining in the Americas.
The duration and extent of the operation, the researchers add, indicates "the techniques required to exploit and process these minerals were transmitted over generations."
Before this find, a North American copper mine dated to between 4,500 and 2,600 years ago was the oldest known in the Americas.
John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).