High in Spain’s eastern Pyrenees, inside a cave that overlooks the Nuria Valley from 2,235 meters above sea level, archaeologists have pulled roughly 200 rock fragments streaked with green mineral patches from layers of ancient hearths. The fragments, which the research team proposes are malachite, a copper carbonate mineral, show clear signs of deliberate heating. According to a peer-reviewed study published in Frontiers in Environmental Archaeology in May 2026, the discovery suggests that Neolithic communities were processing copper ore at extreme altitude more than 7,000 years ago, centuries before the Chalcolithic period traditionally linked to the rise of metallurgy in the western Mediterranean. The study was led by Ermengol Gassiot Ballbè and colleagues at the Universitat Autònoma de Barcelona.
What the excavation uncovered
The site, known locally as Cova 338, sits near the village of Queralbs in Girona province. Researchers excavated an approximately six-square-meter area at the cave’s entrance and identified four distinct occupation layers containing 23 hearths and multiple combustion pits. Scattered among those layers were the green-patched rock fragments, many bearing thermal alteration patterns consistent with intentional heating rather than accidental contact with fire.
“They weren’t burned by accident,” the researchers stated in the study, as quoted in a news release distributed by Frontiers. Gassiot Ballbè and co-authors noted that the density of hearths packed into such a small space, combined with the volume of mineral-bearing fragments, “points to organized, repeated activity” centered on the green rocks.
The excavation also turned up burned stone, the bones of a child, and personal ornaments, all suggesting that people returned to this cave again and again over extended periods. This was not a one-off campsite. The evidence paints a picture of a high-altitude base used for sustained resource extraction alongside everyday domestic life.
Why the find matters for the history of metallurgy
If the green mineral is confirmed as malachite through chemical analysis, Cave 338 would rank among the earliest known copper-processing sites in western Europe. The current consensus places the oldest confirmed copper smelting at sites like Belovode in Serbia, where slag and metal droplets date to around 5000 BCE. Finds from the Balkans and Anatolia have long dominated the narrative of how metallurgy emerged and spread. A verified Neolithic smelting operation in the Pyrenees would challenge the assumption that early copper working radiated outward from southeastern Europe and would rewrite the role of mountain communities in that story.
The altitude alone is striking. At 2,235 meters, Cave 338 is one of the highest locations in the Pyrenees where sustained prehistoric occupation has been documented. That people maintained dozens of hearths and apparently lived with children at this elevation speaks to a level of logistical ambition that scholars had not previously attributed to Neolithic groups in the region.
What still needs to be confirmed
The strongest caveat involves mineral identification. The roughly 200 green-patched fragments are described as “proposed malachite” in the study, based on visual and contextual analysis. The published record does not yet include independent chemical testing, such as X-ray diffraction or scanning electron microscopy, that would rule out other green minerals or non-copper sources of coloration. The Pyrenees do contain copper-bearing geological formations, which makes the malachite identification plausible, but plausible is not the same as proven.
Precise dating is another open question. The study ties the finds to a broad Neolithic timeframe but does not report specific radiocarbon dates for individual hearths or artifact layers. Without that granularity, it is hard to place Cave 338 on a precise timeline alongside competing early smelting sites in southeastern Europe and the Near East. The “7,000 years ago” figure reflects the researchers’ interpretation of the occupation period, but tighter dating would strengthen the claim considerably.
A further unresolved question concerns the thermal thresholds involved. Reducing malachite to copper metal in a charcoal-fueled hearth can begin at temperatures as low as roughly 700 to 800 degrees Celsius, well within the range achievable in purpose-built fire pits. However, the study does not report direct temperature measurements from the hearths, so whether the fires reached the sustained heat needed for full reduction remains an open question. As the authors note, confirming the mineral identity and documenting the thermal conditions together would close the gap between circumstantial evidence and definitive proof of smelting.
There is also the question of where the ore came from. No isotopic or trace-element studies linking the green fragments to specific regional copper deposits have been published. That kind of analysis would reveal whether Neolithic groups mined ore locally at high altitude or carried it up from lower elevations, a distinction with major implications for understanding prehistoric trade networks and seasonal migration in mountain environments.
What comes next for Cave 338
The research team’s next steps will likely determine whether this site enters the textbooks or remains a tantalizing footnote. Laboratory confirmation of malachite, paired with radiocarbon dates pinned to specific hearth layers, would transform a strong circumstantial case into a definitive one. Strontium isotope analysis of the child’s bones could also clarify whether the cave’s occupants were year-round residents of the high valley or seasonal visitors who climbed to the site for specific purposes.
Even without those confirmations, the excavation has already expanded what archaeologists thought possible at extreme altitude during the Neolithic. Twenty-three hearths, hundreds of mineral fragments, and evidence of children living in a cave above 2,000 meters: whatever the green rocks turn out to be, the people who carried them there were doing something deliberate, organized, and far more sophisticated than the traditional picture of early mountain life would suggest.
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*This article was researched with the help of AI, with human editors creating the final content.
