Oldest ocher mine on American continent discovered in Mexico

Diver Christophe Le Maillot documents the rock-crowding activity at La Mina. (Image by Sam Meacham, courtesy of CINDAQ).

Archaeologists and cave divers found in Mexico what they believe is the oldest known mine in the American continent.

In a paper published in the journal Science Advances, the explorers explain that a flooded cave in the southeastern state of Quintana Roo hosts irrefutable evidence of prehistoric mining activities that were carried out some 10,000 to 12,000 years ago.

According to the researchers, lab analyses show that La Mina – ‘The Mine’ in Spanish, the name they gave to the area – was active roughly during the same period when Naia was alive. Naia was a young prehistoric woman whose remains were found in 2014 inside the Hoyo Negro (Black Hole) archaeological site located near Tulum.

Oldest ocher mine in the American continent. (Image by Sam Meacham, courtesy of CINDAQ).

“La Mina is a continuation of Hoyo Negro not only because of their relative geographical proximity but also because the archaeological context of the former greatly complements the existing knowledge surrounding the latter,” said in a media statement Roberto Junco Sánchez, head of the Underwater Archaeology Sub-Directorate at the National Institute of Anthropology, the institution leading the project since 2017 together with the History and Research Centre of the Quintana Roo Aquifer System, known as CINDAQ in Spanish.

Junco Sánchez explained that while the discovery of Naia contributed to the understanding of the ascent, expansion and development of the first Americans, thanks to La Mina it is now possible to know that early humans not only risked their lives by entering the labyrinth of caves in search of water or to escape predators, but they also went inside them for mining purposes, thus altering them and creating cultural modifications within.

Such modifications were observed over a six-kilometre radius of uncharted underwater passageways that were previously concealed behind clusters of rocks and narrow passages. In these areas, various materials were rearranged as a result of archaic human intervention.

Among the elements that caught the explorers’ attention were heaps of coal on the floor, soot on the ceiling of the cave and small carved-out cavities on the ground, where traces of ocher were found. 

The location of the cave system remains confidential for conservation purposes

“The cave’s landscape has been noticeably altered, which leads us to believe that prehistoric humans extracted tonnes of ocher from it, maybe having to light fire pits to illuminate the space,” said Fred Devos, CINDAQ’s co-director and one of the divers who has been exploring the cave for about three years.

Until now, no human skeletal remains have been found, however, rudimentary digging tools, signs —that would have been used in order not to get lost— and stacks of stones left behind by this primitive mining activity have been located. The abundance of ocher filled cavities has led experts to theorize about the rocks themselves being used as tools to excavate and break down the stone.

Next steps

At this point, the team working at La Mina has accumulated 600 hours of diving, 100 immersions and 20,000 photos taken with technologies such as photogrammetry and 360 degrees underwater cameras.

The information gathered during the excursions will now be used by experts from Mexico, Canada and the United States to create a 3D model of the site that allows virtual access to archaeologists.

At the same time, the collected ocher and other materials will be analyzed at the DirectAMS laboratory in Bothell, Washington to know more precisely how old they are.

The DirectAMS lab consultant working on the project, James Chatter, described what his analyses tell him about what an operative La Mina used to look like. “Imagine a flickering light, in the middle of deep darkness, that at once illuminates the red-stained hands of the miners as they strike the ground with hammers made out of stalagmites, while it lights the way for those who carry the ocher through the tunnels until they reach sunlight and the forest floor.”

The location of the cave system remains confidential for conservation purposes.