On an aerial view—even one so far zoomed out that it took in the entirety of Australia, Indonesia, and Southeast Asia—you could easily pick this place out by looking for the gray scar on New Guinea’s southern flank. This was the alluvial spew of the river that flowed down to the Arafura Sea from glaciers along the island’s spine: the highest mountain between the Himalayas and the Andes. Unlike all the other rivers draining that slope—and there were a lot of them, given that the glaciers were melting, and rainfall could exceed ten meters per year—the one that ran through Tuaba was gray because the sediments coming down from the copper mine hadn’t weathered naturally and hadn’t had time to oxidize.