Key PointsLess than a year ago, the U.S. government promised MP Materials a loan and an investment if it would build a new rare-earth magnet factory.Less than a year later, MP Materials is ready to begin.MP's new factory in Texas will cover a significant fraction of America's rare-earth metals demand.10 stocks we like better than MP Materials › Eight months ago, MP Materials (NYSE: MP) made a giant leap. For years -- decades -- MP Materials and …