It is rare, unheard of almost, for a single site to control the global supply of a crucial material. Yet if you want to get high-purity quartz—the kind you need to make those crucibles without which you can’t make silicon wafers—it has to come from Spruce Pine, a small town on the Blue Ridge escarpment in North Carolina. For a long time, this mine—and by extension the entire global supply of high-purity quartz—was operated by a single company, a secretive Belgian business called Sibelco.
