Searching for lithium deposits with satellites

CORNWALL, a rugged peninsula that forms Britain's south-western extremity, has a history of mining going back thousands of years. Its landscape is dotted with the ruins of long-closed tin and copper mines, along with mountains of spoil from the extraction of china clay (also known as kaolin), a business that still clings to life today. Now, though, prospectors are back on the ground. Or, rather, they aren't. Instead, they are peering down from space. And what they are searching for is not tin, n...