Strange green stones, evidence of repeated ancient expeditions, hidden burials, and other discoveries have been made in a remote cave high in the Pyrenees mountains.
The findings were made in a cave located more than 7,300 feet above sea level, revealing evidence that ancient visitors repeatedly endured the hardships of climbing to such altitudes for a period spanning 2,000 years. The question for archaeologists had been why this cave seems to have held such importance.
Now, discoveries at the remote site could potentially alter our understanding of ancient European uses of mountain landscapes in prehistoric times. Of key importance, archaeologists have uncovered ancient hearths that contain small samples of green minerals, which point to ancient mining activities that likely supported ancient metallurgy in the region.
Two Millennia of Human Interest
For more than 2,000 years, ancient Europeans repeatedly traveled to this remote cave, leaving behind evidence of their visits that includes ancient hearths and even a child’s tooth, suggesting the possibility that there may even be hidden graves at the site.
Professor Carlos Tornero, a researcher with the Catalan Institute of Human Paleoecology and Social Evolution, says these discoveries are surprising, since past research suggested such areas would only have been occasionally traversed by humans during periods of migration, rather than becoming destinations.

“For a long time, high-mountain environments were seen as marginal, places prehistoric communities passed through occasionally,” said Tornero, who is the lead author of a new study detailing the findings.
That wasn’t the case with this Cave 338, as archaeologists now call it, which turned out to be a far more unique site.
“We found a really rich archaeological sequence, including multiple combustion structures and a very large number of green mineral fragments,” Tornero recently said. “We can’t say exactly how long people stayed each time, but the repeated use of the space and the density of remains suggest occupations that were short to medium in duration, but happening again and again over long periods of time.”
Evidence of an Ancient Copper Mining Industry
At Cave 338, initial excavations began with a small area spanning six square meters near the cave’s entrance. There, Tornero and the team uncovered evidence of human activity temporally associated with four distinctive layers.
In the most recent layer of human occupation, artifacts from historical periods were found, although in smaller numbers, which suggested that the cave’s use had likely decreased gradually with time. Similar limited use was evidenced in the cave’s deepest layers, where charcoal fragments were discovered with dates indicating human activity as far back as 6,000 years ago.
Within layers two and three, significantly more activity was discernible. Discoveries within these layers included nearly two-dozen hearths, many of which contained burned fragments of a green mineral that researchers believe may be malachite.

If confirmed, this is significant, since malachite is rich in copper and can be processed to extract the metal, meaning that ancient visitors to the cave may have visited the site specifically to mine this unique green mineral. Cave 338 would therefore represent a very high-altitude mining camp, which ancient Europeans somehow discovered and repeatedly visited.
When Fire Heats the Green Stone
Based on radiocarbon dating, hearths located in the site’s second layer are approximately 3,000 years old, while those in the layer directly beneath it date to between 4,000 and 5,000 years ago.
Dr. Julia Montes-Landa of the University of Granada, who was a co-author of the new paper, says that evidence suggests many of the fragments were thermally altered—in other words, they were intentionally exposed to fire—while some of the samples found at the site were not.
This, she argues, “clearly suggests that fire played an important role in their processing and that there was a deliberate intention behind it.”
“They weren’t burned by accident,” Montes-Landa says.
Another indication of ancient industrial activity at the site involves the placement of the hearths in layers two and three, many of which overlap, which strongly suggests reuse. However, more than one area containing overlapping hearths is present, which also suggests that while reuse occurred, it took place in successive periods of visitation throughout time.
Hidden Burials and Prehistoric Artifacts
In addition to ancient evidence of mining and thermal alteration of stone, within the site’s third layer, a small amount of human remains—an ancient baby tooth and a finger bone believed to have belonged to a child—were found.
Such scant remains do not provide context for the cause of death or whether the remains came from the same individual. However, it does point to the possibility of hidden burials that may exist in other portions of the cave.
In addition to human remains, prehistoric artifacts were found at the site, which date to the second millennium BC, including a shell pendant and another made from a bear’s tooth.
“The shell pendant is interesting because it has parallels in other sites in Catalonia, which suggests shared traditions or connections between different communities,” Tornero said. “The bear tooth pendant is much less common.”
“That might point to something more specific or symbolic, possibly linked to the local environment,” Tornero suggests.
Lingering Questions
Obviously, 338 held significance to ancient inhabitants of the region, since, despite the daunting trek reaching it would have required, humans clearly returned there over and over again for a period of at least two thousand years, although evidence of human presence at the location extends to as much as double that amount of time.
Going forward, Tornero, Montes-Landa, and their colleagues hope that future excavations may reveal additional clues about who had been coming here for so long, and what specifically attracted them to the cave.
Of key significance will also be confirmation that the mineral contains copper.
“The identification of the green mineral as malachite is still preliminary,” Tornero says, adding that ongoing research “will provide final answers shortly.”
Much work remains to be done at the site, and Tornero and his team plan to resume excavations there later this year.
“The excavation hasn’t yet reached the full depth of the site,” Tornero said, “so the sequence is not completely documented.”
“This summer we will continue the archaeological work,” Tornero added.
For now, Cave 338 already shows that even some of the most remote areas of the Pyrenees could have played significant roles in the way ancient humans utilized the land and its resources.
“As such, the site provides a key reference framework for understanding high-mountain occupation, resource exploitation and mobility dynamics in the Pyrenees during later prehistory,” the authors write in their recent paper.
The team’s paper, “Beyond 2,000 meters, first evidence of intense prehistoric occupation in the Pyrenees,” appeared in Frontiers in Environmental Archaeology.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.
