Excavations from 2021 to 2023 at Cave 338 in the eastern Pyrenees in Spain near the border with France uncovered well-defined archaeological layers of human occupation in phases from the early 5th millennium B.C. to the late 1st millennium B.C. At above 7,333 feet (2,235 meters) above sea level, its the highest-altitude cave with sustained prehistoric human occupation in the Pyrenees.Archaeologists unearthed four layers of occupation: a thin top layer with a few artifacts from historical periods indicating it was barely used, an oldest layer consisting solely of charcoal fragments and two middle layers with dense remains of combustion pits, animal bones, ceramic vessels and an extraordinary assemblage of green mineral fragments believed to be malachite.Almost 200 pieces of green stone fragments were found alongside charcoal in 23 combustion pits. Malachite is not native to the cave so must have been transported there. Researchers believe it was brought to the cave to convert the mineral into copper. Heating malachite breaks it down into carbon dioxide and copper oxide. Adding charcoal then releases the carbon dioxide and leave a nugget of copper behind. Many of the fragments were This is one of the earliest archaeological contexts documenting prehistoric high altitude copper mining in Europe.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 werent burned by accident.The hearths cut across each other, indicating that the visitors reused this space frequently, but are still distinct, which suggests that those visits were separated by plenty of time. Radiocarbon dating puts the hearth found in the second layer at about 3,000 years old, while the hearths in the third layer are around 5,500 to 4,000 years old.The excavation also uncovered the remains of at least one child and jewelry. A finger bone and a baby tooth from a child around 11 years of age were found in the third layer. Its not currently possible to determine if the two came from the same child, but they do indicate the site was used for burials and there may be more to be found deeper in the cave. A shell pendant and a brown bear tooth pendant dating to around the second millennium B.C. were found in the second layer. There are comparable shell pendants known from prehistoric sites in Catalonia, which suggests ties between communities or shared cultural traditions, while the bear tooth is a rarity that may have been found in the cave or environs.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. We cant 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.The study has been published in the journalFrontiers in Environmental Archaeology and can be read in its entirety here.