Mountain Pass: a rare earths operation in the United States
Mountain Pass is a hard-rock mine producing rare earths in San Bernardino County, California, the United States, operated by MP Materials. The sources report 50,692 MTs (metric tons) of REO contained in rare earth concentrate ('REO Production Volume') for CY2025; the basis is 100%, as reported by the operator. In rare earths content, whole-operation output for CY2025 is 50,692 tonnes: about 13% of world rare earths output in 2025 and about 99% of the United States'; it is the only operation on this site whose output can be stated in rare earths content.
Who owns and operates it?
| Owner | Interest | As of |
|---|---|---|
| MP Materials | 100% | 31 December 2025 |
How much does it produce?
| Period | Output | Basis | Where in the source |
|---|---|---|---|
| CY2025 | 50,692 MTs (metric tons) of REO contained in rare earth concentrate ('REO Production Volume') | 100%, as reported by the operator | printed p.49, Materials segment KPI table, 'REO Production Volume (MTs)'; definition printed p.42; highlights printed p.37 · MP Materials Corp. |
| CY2024 | 45,455 MTs (metric tons) of REO contained in rare earth concentrate ('REO Production Volume') | 100%, as reported by the operator | printed p.49, same row, 2024 column · MP Materials Corp. |
Between CY2024 and CY2025 the reported figure rose by 11.5%, in the same unit and on the same basis.
How the rare earths-content figure is worked out. MP Materials reports 50,692 metric tons of REO contained in the rare earth concentrate produced at Mountain Pass in 2025. It owns and operates the site, so the figure covers the whole operation. World mine production of rare earths in 2025 was 390,000 tonnes (USGS Mineral Commodity Summaries 2026); the United States produced 51,000 tonnes.
Status: operating, as of 30 June 2026.
- The figure is production of REO contained in concentrate. REO Sales Volume was 8,922 MTs in 2025 (32,703 MTs in 2024), because the company ceased all product sales to China in July 2025 and refines a larger share of its concentrate into NdPr oxide and metal. The 10-K reports 2,599 MTs of NdPr oxide produced in 2025, which is a separated product and is not added to the concentrate figure.
- USGS prints 51,000 t of REO in mineral concentrates for the United States in 2025 and cites the figure as reported; USGS says that line excludes monazite concentrates.
- The 10-K describes the Mountain Pass deposit as hosted in monazitic carbonatites, with bastnaesite as the principal ore mineral (printed p.29).
How does it compare?
Other rare earths operations on this site: Mt Weld. See where rare earths comes from for the country totals, the country page for United States, and MP Materials for its other operations here.
Sources
- MP Materials Corp.: Form 10-K for the year ended 31 December 2025 (annual report (SEC 10-K, filed 2026-02-26), FY2025 (calendar), with 2024 and 2023 comparatives). Opened 3 November 2026; used: printed pp.1, 28, 29, 35, 37, 42, 49.
- MP Materials Corp.: Form 10-Q for the quarter ended 30 June 2026 (quarterly report (SEC 10-Q, filed 2026-08-07), Q2 2026 and six months to 30 June 2026). Opened 3 November 2026; used: printed p.38 (Materials segment KPI table).
- U.S. Geological Survey: Mineral Commodity Summaries 2026: Rare earths (government statistical summary, 2025 (world and country mine production)). Opened 3 November 2026; used: world and country mine production table.
Method and limits
- Reported, not estimated. Output is the figure the operator or owner published, in the unit it used. This site does not estimate output where none is published.
- Shares. A share divides output in rare earths content by the USGS world or country total for 2025. Where the operator's year is a fiscal year or the unit is a concentrate or a carbonate equivalent, the share is approximate or not given.
- Whole operation or owner's share. The basis column says which. A joint venture's output is never counted twice.
- Partial list. Only operations with a published figure are listed, so the rank is among those on this site, not among every rare earths mine. Shares of a country's output mix periods and bases, so treat them as indicative.
- Made with AI assistance, checked against sources. The facts were gathered from the documents above by AI-assisted research and re-checked against those documents by a second, independent pass; the page text is generated from the data. No professional review took place. How the site is made. To report an error, contact us; fixes are logged on the corrections page.