Missouri · state page

Rare earth mines in Missouri: one historic deposit, none tracked

Missouri has no tracked rare earth mine, plant or company. The USGS describes one historic deposit here, Pea Ridge: an iron mine that ran from 1964 to 2001, with rare earths in breccia pipes and in apatite tailings. Its owner, Caldera Holdings of St. Louis, says it plans to reprocess waste from the old mine for rare earths and to develop phosphate (company-reported, Mar 2026). This directory found no permit, resource estimate or construction.

The USGS record for Pea Ridge comes from its 2010 report and its 2002 database, and it records no rare earth production. The page below sets that record beside the activity found since 2024.

Verified through Oct 1, 2026

See the deposit All historic deposits

Tracked sites and companies: 0None on the map or in the registry
USGS-described deposit: 1Pea Ridge
USGS 2002 database records: 1Site recorded in Missouri
Latest activity found: Mar 2026Caldera Holdings (press report)

Which historic rare earth deposit is in Missouri?

Missouri has one principal historic or prospect deposit, Pea Ridge, in Washington County, about 97 km southwest of St. Louis. The USGS record below is set beside what has been found since 2024, which this directory classes as "company program reported".

Pea Ridge

Washington County, about 97 km southwest of St. Louis

Iron oxide and apatite Company program

The USGS record

Type: Four rare earth breccia pipes cutting a magnetite and hematite iron orebody, with rare earths in apatite tailings
Minerals: Monazite and xenotime in apatite
How it was found: An iron mine from 1964 to 2001.
USGS status, 2010: No active development in 2010; a company planned to reclaim iron ore.
Production: More than 27 million tonnes of iron products, 1964 to 2001. No rare earths.
Resource figures: A 1990 Bureau of Mines report: about 600,000 t of rare earth reserves at 12% oxide in the breccia pipes. The USGS notes the supporting data are missing.An old figure under no modern reporting code, not a reserve.

Found since 2024

Mar 16, 2026 Caldera Holdings (St. Louis): The owner says it plans to reprocess waste from the old iron mine for rare earths, develop phosphate for fertilizer and later return to underground mining; its chairman says partners are preparing to invest more than $1B. No permit or resource estimate was verified here. Press report KBIA: amid trade wars, Missouri's mining industry digs deep (Mar 16, 2026)

A company reports rare earth work, a plan, a permit or sales at the site.

Pea Ridge on the historic deposits page · USGS 2010, page 57 · USGS 2002 record 274

What has been claimed about the rare earths at Pea Ridge?

A 2023 Oak Ridge National Laboratory release on a license to the owner describes Pea Ridge as fully permitted and holding 700,000 tons of rare earths, and the owner's chairman told KBIA in Mar 2026 that partners plan to invest more than $1B. This directory has verified neither the permit nor the tonnage.

The 2023 release On Nov 28, 2023 Oak Ridge National Laboratory announced a nonexclusive research and development license of its membrane solvent extraction process to the owner (spelled Caldera Holding in the release). The release describes Pea Ridge as the only fully permitted domestic source of heavy rare earths and says it holds 700,000 tons of rare earths in three deposits, including dysprosium and terbium. It gives no source or reporting code for those figures. Oak Ridge National Laboratory: owner of US heavy rare earth mine licenses ORNL separation technology (Nov 28, 2023)
What a research license is A research and development license lets the owner test a separation process on its ore. It is not a plant, a permit or a sales contract, and the release does not say that any of those exists. The USGS's own figure for the site is older and smaller: about 600,000 t of rare earth reserves at 12% oxide, from a 1990 Bureau of Mines report whose supporting data the USGS says are missing. Oak Ridge National Laboratory: owner of US heavy rare earth mine licenses ORNL separation technology (Nov 28, 2023)

Who licenses thorium-bearing rare earth material in Missouri?

The Nuclear Regulatory Commission does. Missouri is not an Agreement State, so the NRC, not a state agency, licenses source material there: uranium, thorium or ore with 0.05% or more of either by weight. Unrefined and unprocessed ore is exempt, so the question arises when ore is processed.

Not an Agreement State

The USGS lists monazite at Pea Ridge, and monazite carries thorium: the USGS gives 0 to 20% thorium oxide for the mineral. A plan that processes that material would raise the licensing question.

The NRC and Agreement State page explains the 0.05% and 0.25% limits and how the decision runs.

Which neighboring states have rare earth projects?

Nebraska and Oklahoma border Missouri and have tracked rare earth sites, companies or pilots. Arkansas and Illinois border it and have a page for a historic deposit only.

All states: rare earth mines, projects and companies by US state. A tracked state has a mine, plant, company or pilot in the directory; a state marked H has a page for a historic deposit only.

Questions about rare earth in Missouri

Does Missouri have rare earth mines?

No. Missouri has no tracked rare earth mine, plant or company, and the only active primary rare earth mine in the United States is Mountain Pass in California. The USGS describes one historic deposit here, Pea Ridge, and records no rare earth production there.

Is Pea Ridge being developed for rare earths?

Its owner says it plans to, and reports partners preparing to invest more than $1B (company-reported, Mar 2026). This directory found no permit, resource estimate or construction, so Pea Ridge is not tracked as a project. It is on the historic deposits page.

What rare earth minerals occur at Pea Ridge?

The USGS 2002 database lists monazite, xenotime and allanite at Pea Ridge. Its 2010 report describes monazite and xenotime in apatite. This site has pages on monazite, xenotime and allanite.

How much rare earth does Pea Ridge hold?

This directory found no estimate under a modern reporting code. The USGS 2002 database lists 0.6 million tonnes at 12% rare earth oxide. Its 2010 report cites a 1990 Bureau of Mines figure of about 600,000 t of rare earth reserves at 12% oxide and says the supporting data are missing. A 2023 Oak Ridge National Laboratory release describes 700,000 tons of rare earths, without a source or reporting code. None of these figures is comparable to the tracked projects; see how to read resource estimates.

Is Missouri an NRC Agreement State?

No. Missouri is not an Agreement State, so the NRC, not a state agency, licenses source material there: uranium, thorium or ore with 0.05% or more of either by weight. Unrefined and unprocessed ore is exempt. See NRC and Agreement State licensing for rare earth projects.

Who owns Pea Ridge?

Caldera Holdings, based in St. Louis, owns the site (KBIA, Mar 2026). The 2023 Oak Ridge National Laboratory release names the owner Caldera Holding. The iron mine itself closed in 2001 after producing more than 27 million tonnes of iron products (USGS).

Sources and verification

Each profile lists its sources, a confidence grade and a verification date. Order of authority: official records (SEC filings, agency documents), company documents and technical reports, research papers, then independent press. Syndicated copies and reference works are labeled and are never the only source for a number. Company-reported figures are labeled as such, and non-binding deals are labeled "letter of intent" or "conditional".

KBIA: amid trade wars, Missouri's mining industry digs deep (Mar 16, 2026) Independent press
Oak Ridge National Laboratory: owner of US heavy rare earth mine licenses ORNL separation technology (Nov 28, 2023) Official record
NRC: Agreement States Official record
USGS: The Principal Rare Earth Elements Deposits of the United States (Scientific Investigations Report 2010-5220) Official record
USGS Open-File Report 02-189: rare earth element mines, deposits and occurrences (Orris and Grauch, 2002) Official record
USGS Mineral Commodity Summaries 2026 Official record

Tags show what kind of source each link is. How sources are ranked

Related: historic and prospect deposits, rare earth mines in the US, rare earth companies in the US, the map of tracked sites, and the mineral pages on monazite, xenotime and allanite. The NRC and Agreement State page covers licensing.