The find challenges assumptions that people in the region thousands of years ago did not spend much time at high altitudes Archaeologists think the green minerals found in the cave might be malachite, which is treated and processed to make copper. Maria D. Guillén / IPHES-CERCA To get to Cave 338, high in the Pyrenees mountains , you must go primarily by foot. That’s exactly what a team of archaeologists did during a recent excavation—and likely exactly what people did thousands of years ago, when the area may have served as a copper processing site. A new study published this week in Frontiers in Environmental Archaeology   found hearths, jewelry, children’s bones and a green mineral that researchers think is malachite , a source for copper. Previously, archaeologists thought that prehistoric peoples in that region rarely spent time at high altitudes. But this new discovery proves otherwise.…