Mountain Pass: location, owner, status and timeline (2026)

The deposit is a carbonatite, an igneous rock rich in carbonate minerals, that formed about 1.4 billion years ago. The main rare earth mineral is bastnaesite, a rare earth fluorocarbonate. The ore body is roughly 200 feet thick and 2,300 feet long, and MP Materials describes it as one of the highest-grade rare earth resources in the world.

Colosseum, a gold-first exploration project inside the Mojave National Preserve, lies about 10 km north of Mountain Pass. It is a separate project with a different owner and no estimated rare earth resource.

MP Materials bought the mine in July 2017 and resumed operations in January 2018. It listed on the NYSE on Nov 18, 2020 after a merger with Fortress Value Acquisition Corp. MP Materials is headquartered in Las Vegas, Nevada, and James Litinsky is its chairman and chief executive.

Earlier owners ran the mine under the Molycorp name. Molybdenum Corporation of America began small-scale production in 1952, Union Oil acquired Molycorp in 1977, Chevron took over in 2005 and sold the mine in 2008 to Molycorp Minerals LLC. That company filed for Chapter 11 bankruptcy in 2015 with about $1.4B of debt, and the mine shut down that August.

Shareholder listings from 2024 included Litinsky, Vanguard, BlackRock, Shenghe Resources (a Chinese company) and Hancock Prospecting among the larger holders (Wikipedia). See MP Materials: what it does, projects, funding and status for the company profile.

Mountain Pass produced 50,692 t of rare earth oxide (REO) in concentrate in 2025, 12% more than in 2024. NdPr oxide output was 2,599 t, double the 2024 level, and NdPr sales were 1,994 t. USGS estimates total US mine production at 51,000 t of rare earth oxide equivalent in 2025, so Mountain Pass is almost all of it.

In 2026 the mine produced 12,983 t of REO in Q1 (917 t of NdPr oxide) and 11,072 t in Q2 (840 t of NdPr oxide). MP Materials expects Q3 NdPr production above 1,000 t as reliability and throughput improve (company statement).

The processing chain has five steps: mining and crushing, milling and flotation, roasting, leaching and impurity removal, separation, and product finishing. The company reports that about 95% of its beneficiation water is recycled and that it stacks dry tailings.

The first heavy rare earth separation circuit was mechanically complete in May 2026, and MP Materials expects to start producing terbium and dysprosium later in 2026. It plans first samarium production in 2028 and has signed a long-term offtake for separated gadolinium with a new US aerospace and defense customer (Q2 2026).

Downstream, MP Materials makes NdPr metal and NdFeB magnets at its Independence plant in Fort Worth, Texas. The plant began making magnets in Dec 2025 and has delivered qualification samples to General Motors, with commercial shipments expected in Q4 2026. Apple signed a $500M agreement in Jul 2025 for magnets made from recycled material, with shipments expected from 2027. A second campus, 10X in Northlake, Texas, targets 7,000 t/yr of magnets from 2028.

Wastewater pipeline breaches shut the separation plant's refined-product output in 1998, and mining was suspended in 2002 when the tailings pond reached capacity. Historical accounts describe about 60 spills between 1984 and 1998 that released roughly 600,000 US gallons of radioactive and other hazardous wastewater to the desert, and more than $1.4M in fines and settlements. The county approved a 30-year operating permit in 2004 after a cleanup plan.

MP Materials stated in earlier annual reports that it expects to extend the county permits to at least 2053. No pending lawsuit over the mine itself was found in the sources checked. The company disclosed that its Department of War agreement bars sales of its products to China, and it lists China-related supply and trade policy as a business risk.