Fresh from church on a cool, overcast Sunday morning in Spruce Pine, North Carolina, Alex Glover slides onto the plastic bench of a McDonald’s booth. He rummages through his knapsack, then pulls out a plastic sandwich bag full of white powder. “I hope we don’t get arrested,” he says. “Someone might get the wrong idea.” Glover is a recently retired geologist who has spent decades hunting for valuable minerals in the hillsides and hollows of the Appalachian Mountains that surround this tiny town. He is a small, rounded man with little oval glasses, a neat white mustache, and matching hair clamped under a Jeep baseball cap. He speaks with a medium‑strength drawl that emphasizes the first syllable and stretches some vowels, such that we’re drinking CAWWfee as he explains why this remote area is so tremendously important to the rest of the world. Spruce Pine is not a wealthy place. Its downtown consists of a somnambulant train station across the street from a couple of blocks of two‑story brick buildings, including a long‑closed movie theater and several empty storefronts. The wooded mountains surrounding it, though, are rich in all kinds of desirable rocks, some valued for their ind...