Rare earth miner and processor MP Materials (MP -4.88%) had quite the week to remember, both operationally and on the stock market. On the back of some quite favorable news, the company's shares raced more than 16% higher over the course of the week, according to data compiled by S&P Global Market Intelligence.A rare businessMP Materials owns and operates the only rare earth mine in the U.S. Rare earths, for those unfamiliar, are metals that are used in the manufacture of specialty magnets used in popular h ...