Light pink segregations of Bastnasite-(Ce) in brown carbonate matrix.
The REE content of the Mountain Pass district was first discovered in 1949 by uranium prospectors. Mountain Pass is a massive carbonatite called the Sulfide Queen, which host the rare earth minerals. The typical ore contains 10-15% Bastnasite. It is the largest known mass of high-grade REE deposit in the USA.
The first operator was Molycorp which ceased mining in 2002 when its permit expired. Molycorp had plans to reopen, but by 2105 they went bankrupt. The mine's new owner is MP Materials. In December of 2021 General Motors and MP Materials entered long-term supply agreement to supply rare earth magnet production in the U.S. In 2021 production of 42,413 metric tons represents highest annual primary rare earth production in U.S. history. In February of 2022 MP Materials secured Department of Defense contract to supply processed heavy rare earths. MP produces primarily neodymium and praseodymium for powerful magnets used in electric cars, windmill turbines, drones, robuts, and military jets. Please click here for a good video overview of Mountain Pass as operated by MP Materials.