The Mountain Pass Rare Earth Mine and Processing Facility, owned by MP Materials, is an open-pit mine of rare-earth elements on the south flank of the Clark Mountain Range in California,  southwest of Las Vegas, Nevada. In 2020 the mine supplied 15.8% of the world's rare-earth production. It is the only rare-earth mining and processing facility in the United States.
As of 2022, work is ongoing to restore processing capabilities for domestic light rare-earth elements (LREEs) and work has been funded by the United States Department of Defense to restore processing capabilities for heavy rare-earth metals (HREEs) to alleviate supply chain risk.