For Centuries, People Gathered at This Cave High in the Spanish Mountains. Green Rocks Could Show Us Why

Cave 338 is far up in the mountains and out of the way, so why was it such a popular destination?

The hike to Cave 338 is tough. You start at the Monastery of Núria in the eastern Pyrenees, which is already pretty high. Then, you climb a steep, punishing slope for 45 minutes. At 2,235 meters above sea level, temperatures drop and the wind starts to bite.

Yet, for hundreds of years, people kept gathering to this spot. Now, a new study may have figured out why.

Judging by what ancient people left behind, Cave 338 was a work site, a high-altitude mining processing camp. Archaeologists found repeated fire pits, handmade pottery, butchered and burned animal bones, and, most strikingly, more than 170 fragments of green copper-rich stone, probably malachite, that doesn’t naturally occur inside the cave.

A Rare Archaeological Site

Most people know Spain for its lush beaches and lovely food, but Spain is actually one of the most mountainous countries in Europe and has the second-highest average altitude on the continent. The Pyrenees mountains, which separate northern Spain from southern France, are the country’s highest. The range features over 129 peaks exceeding 3,000 meters (9,843 ft) in altitude, with the highest point, Aneto Peak, reaching 3,404 meters (11,168 ft).

For years, archaeologists knew people entered the Pyrenees deep in prehistory. The broader region holds evidence of activity throughout the Paleolithic, and up until the Bronze Age. But the story changed above 2,000 meters. At those altitudes, prehistoric sites are rare, hard to excavate, and often poorly preserved. It’s not that hard to climb them nowadays when we have equipment and maps, but for prehistoric population, it was a big challenge, with little upside.

So, the standard idea was that people lived in the region and sometimes climbed high, but mostly for short, low-intensity visits.

Cave 338 breaks that pattern.

The cave is relatively small, but it preserved its history unusually well. The actual cavity is just over 100 square meters (around 1000 square feet), with two small caves separated by several meters. The larger chamber narrows into a gallery about 28 meters long.

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Archaeologists had known that this cave was used by people. But in the new study, they showed that the cave was used longer (and more intensely) than previously thought.

“For a long time, high-mountain environments were seen as marginal, places prehistoric communities passed through occasionally,” said Prof Carlos Tornero of the Catalan Institute of Human Paleoecology and Social Evolution, lead author of the article in Frontiers in Environmental Archaeology. “But we found a really rich archaeological sequence, including multiple combustion structures and a very large number of green mineral fragments.

Green Treasure in the Dark

The first surface remains were uncovered in 2010, and a test pit was dug in 2012. This new study presents findings from excavations carried out from 2021 to 2023.

In this period, archaeologists managed to dig only the first six square meters near the cave entrance. But even that small window yielded remarkable findings. They found 23 fire pits, including some that cut into earlier pits. This is already an important clue, showing that people didn’t just stumble upon the cave again and again. They left and returned and, often enough, built on existing structures. Overall, the deposits preserve repeated visits over thousands of years, from at least the early 5th millennium B.C. to the late 1st millennium B.C.

“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,” adds Tornero. 

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The team also found 333 ceramic fragments, as well as two human remains and numerous animal remains. The human finds are too limited to draw firm conclusions, but the authors note that the cave may also have had a funerary role.

But perhaps the most intriguing finds are 170 chunks of vibrant green rock. This is malachite, a copper-rich mineral. These rocks don’t belong in the cave naturally and furthermore, many of them seem to be burned. The likely explanation is that prehistoric people hauled these heavy stones up the mountain and brought them into the cave to be processed.

“Many of these fragments are thermally altered, while other materials in the cave are not, which clearly suggests that fire played an important role in their processing and that there was a deliberate intention behind it,” said Dr Julia Montes-Landa of the University of Granada, co-author. “In other words, they weren’t burned by accident.” 

A Surprising Mining Site

The actual mining wouldn’t have happen in the cave. Instead, the evidence points to a logistical station: a place where people returned to seasonally, bringing with them the tools and whatever else they needed. Simply put, it was a mineral workshop and processing station. If this is confirmed, it would offer rare evidence or the systematic exploitation of copper in that period. It would also make the cave one of the earliest high-altitude mineral exploitation contexts known in Europe.

But the cave still has plenty of mysteries. Evidence points to brief, but organized stays. Animal remains include sheep or goat, pig, dog or other canids, hare, bird and brown bear, but it’s not clear whether people hunted or brought the meat. They were eating meat, processing hides, and likely milking their herds at over 2,000 meters.

The combustion pits, crushed green mineral fragments, limited food remains, sparse stone-tool maintenance debris, and ceramics all point toward short visits organized around specific tasks.

But why go so high up in the mountains?

It’s possible that because the cave was so high, it was sheltered. It may have been close to extraction sites. There is copper-bearing geology in the broader region, but archaeologists haven’t yet identified such a mining site closeby. It may have been a favorable site because it was out of the view of prying eyes, and because fuel (lumber) was plentiful. But this is just a speculation, not confirmed yet.

Copper-rich minerals mattered in late prehistory. Malachite can be used as a green pigment and it can also signal copper ore. The minerals may have been used either for pigmentation or for metallurgical applications. Of course, it’s also possible that this involved some kind of ritual.

So What Should We Take From Cave 338?

There are plenty of yet-unanswered questions, and archaeologists have only excavated a small part of the cave. But already, they have some pretty intriguing conclusions.

First, the high mountains in Europe (or at least in Spain) were more than empty backdrops. They were known, named, navigated, and used.

Second, prehistoric mobility was purposeful and skilled. People had the ability and the will to reach inaccessible places regularly, while likely carrying a lot of baggage.

Third, resource extraction has deep roots in places we often imagine as untouched wilderness. Long before modern mining scarred mountainsides, small groups climbed into alpine zones to gather and process valued stone.

Ultimately, though the story is still unfinished. The excavators plan more work to expand the excavation area, study pollen and plant remains, analyze animal-resource use, and figure out where the minerals came from. Once researchers pin down this origin, Cave 338 may tell us not only that ancient people climbed high, but exactly what they were chasing.

The study was published in Frontiers in Environmental Archaeology.