MP Materials (MP 0.94%) is a unique company with a crucial role to play in America's defense policy and its geostrategic positioning. Currently, it's the only company operating a rare-earth mine and processing facility in the U.S., and it has recently become a partner of the Department of Defense and Apple. Does that make it a stock likely to turn investors into millionaires over time?MP Materials stock is on a rollThere's no other way to put it. The stock is up a whopping 305% year to date as of the time o ...