A chunk of magnetite guards the office door at the Pea Ridge iron mine near Sullivan, Mo., a mascot of the mine’s past and future. When Jim Kennedy bought the mine in 2001, he’d planned to restart production on a high-grade iron ore deposit. He didn’t realize he was sitting on a mother lode of 600,000 metric tons of high-grade rare earth elements -- elements the U.S. is desperately hungry for. Four years ago, he almost threw away reams of documents describing Pea Ridge’s deposit. “Nobody bothered to tell me about it,” he said.