Inside A Pyrenees Cave, Archaeologists Find Green Rocks, Pendants, And Prehistoric Secrets

Researchers Find Earliest Known High-Altitude Mineral Processing Site

A cave perched nearly a mile and a half above sea level in the Pyrenees mountains has challenged a long-held assumption about prehistoric life at high altitude. Between 2021 and 2023, archaeologists pulled more than 170 chunks of vivid green rock from its layered floors, along with fire pits, animal bones, and handmade pottery. The green rock is most likely malachite, a copper-rich mineral that someone carried up the mountain, brought inside, and processed in the cave during repeated prehistoric visits spanning from the early fifth millennium BC to the late first millennium BC.

Known as Cave 338, the site sits at about 7,300 feet above sea level in the eastern Pyrenees, in the municipality of Queralbs in northeastern Spain. Until now, researchers largely assumed that prehistoric people who ventured above roughly 6,500 feet in this mountain range did so briefly. A quick stop on the way somewhere else, maybe a night or two of shelter. Cave 338 challenges that assumption. Its deposits are dense, layered, and packed with all the evidence of people living and working there repeatedly, across thousands of years.

“Cave 338 was not a marginal or sporadically used shelter, but rather a repeatedly occupied logistical site integrated within structured seasonal mobility systems,” the researchers wrote. Put simply, this wasn’t a rest stop. It was a working camp woven into how ancient communities moved through and used the high mountains over thousands of years.

Pyrenees Cave Upends What Archaeologists Thought About Prehistoric High-Altitude Life

Led by Carlos Tornero of the Autonomous University of Barcelona, the team excavated a roughly 65-square-foot area inside the cave’s entrance in 2021 and 2023. Getting there was a project in itself. No motor vehicle can reach the Núria Valley where the cave is located. Researchers took a rack railway, then hiked roughly 45 minutes up a steep slope. Every bucket of excavated dirt had to be hauled back down by hand to a monastery base camp, where it was washed through sieves and sorted for bone, charcoal, pottery, and mineral fragments.

What they found justified the effort. Researchers documented 43 distinct sediment layers and 23 pit-shaped fire features, essentially hearths dug into the cave floor, used, filled in, and then dug again by later visitors. Radiocarbon dating of charcoal placed the cave’s occupation across several distinct phases, stretching from at least the early fifth millennium BC through the late first millennium BC. Earlier test excavations also identified a phase dated to the late fourth millennium BC and a medieval-era use around the 11th to 12th centuries AD. Cave 338 currently stands as the highest-altitude prehistoric cave site with sustained occupation documented in the Pyrenees. Findings were published in the journal Frontiers in Environmental Archaeology.

Green Rocks and Fire Pits: Prehistoric Copper-Mineral Processing at 7,300 Feet

Most eye-catching was the sheer volume of green mineral fragments found throughout the layers. More than 170 hand-sized or smaller chunks were pulled out during excavation, and a large number of tiny fragments turned up in the sieve. Vivid green coloring points strongly to malachite, though chemical and structural analyses are still ongoing to confirm the identification. Some pieces also showed patches of blue, possibly from a related copper-bearing mineral. Critically, these minerals do not occur naturally inside the cave. Someone had to bring them in from elsewhere, and the source area has not yet been identified.

Fragments were found concentrated inside and around the fire pits, across multiple layers spanning different time periods. Researchers describe this pattern as “systematic exploitation of copper-rich minerals in a high-mountain environment,” calling it unprecedented for the Pyrenees and one of the earliest high-altitude examples of mineral processing documented in Europe. What exactly people were doing with the minerals remains under investigation, but the deliberate, repeated transport of these rocks to a cave full of fire pits points to organized, purposeful work.

A Bear Tooth Pendant and a Seashell: Personal Objects Found Far Above the Treeline

Beyond the minerals, the cave yielded a varied snapshot of prehistoric life. Researchers analyzed 945 animal bone fragments, identifying 93 to specific species. Sheep and goat bones dominated, with smaller numbers of pig, dog, brown bear, and rabbit. Some bones showed butchering marks, intentional fracturing, and burning, pointing to meals eaten inside the cave.

Two items stood out as personal ornaments. A shell from a marine clam and a lower front tooth from a brown bear both had holes drilled through them, apparently so they could be worn as pendants. A marine shell this far up in the mountains points to connections with coastal communities or long-distance trade, though the exact route remains unknown.

Two small human remains also turned up: a finger bone and a baby tooth, possibly from the same child, estimated at about 11.5 years old. Researchers note that the cave may have had a funerary role during this phase, though more excavation is needed to confirm it.

For decades, the standard story about prehistoric life above 6,500 feet in the Pyrenees went something like this: people passed through, camped briefly, and moved on. Cave 338 tells a different story outright, one of a place where people came to work, eat, and very possibly bury their dead, repeatedly, across thousands of years.

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