Highlights

• MP Materials plans to commission its heavy rare earth (HREE) refinery by mid-2026.
• The target production is 200 metric tons per year of dysprosium and terbium to support 10,000 MT magnet production.
• The project is backed by a $150 million Department of Defense (DoD) loan and DoD's 15% ownership stake.
• The company has stockpiled over 200 metric tons of SEG+ feedstock containing 4% dysprosium and terbium from the Mountain Pass mine.
• MP Materials plans to integrate third-party sources and an Apple-backed recycling facility for a closed-loop domestic supply.
• Missouri's Pea Ridge Mine is a potential backup feedstock source with approximately 20% rare earth oxide (REO) content in breccia pipes.
• There are timeline and execution risks as MP Materials works against China's continued dominance in HREE separation and refining.

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The flagship “10X” initiative by MP Materials aims to rebuild a full U.S. mine-to-magnet supply chain – from the open-pit ore in California to magnet production in Texas. And Apple, as the company, reported in its recent quarterly investor report, has already transferred the first payment of $500 million for a magnet recycling effort. With the Department of Defense (DoD or Department of War) now owning 15% of MP Materials, the stakes are big—with huge potential, but the clock is ticking. In particular, the heavy rare earths (HREEs) — notably dysprosium (Dy) and terbium (Tb) — remain the potential bottleneck. Without sufficient quantities of Dy and Tb, the magnets needed for electric vehicles, wind turbines and defense systems simply cannot perform in high-temperature environments.

MP’s Positioning

MP already owns and operates the Mountain Pass Mine, California — the only large-scale U.S. rare-earth mine. Rare Earth Exchanges (REEx) refers to this as America’s rare earth treasure trove and recently reported on their quarterly report.

On its website, the company lists a product called “SEG+”, described as a high-value heavy rare earth feedstock that contains approximately 4% Dy + Tb on a total-rare-earth-oxide basis. MP Materials states that REEx has reported that SEG+ will feed its planned heavy-rare-earth separation circuits, and that it has stockpiled over 200 metric tons of SEG+ feedstock. Further, pointed out by consultancy SFA Oxford, MP's public disclosures (opens in a new tab) and the DoD deal indicate that heavy-rare-earth separation capability is under active development, backed by a $150 million DoD loan and planned to be completed by 2026.

But do they have sufficient capability by next year?

That’s the big question.  MP Materials is confident that the firm will achieve aggressive milestones.  REEx suggests that while MP is making meaningful progress, the timeline remains ambitious. Independent commentary notes that full on-shoring of HREE separation — the most technically challenging part — may take 5-7 years. MP has declared a strong intent, but the step from a stockpiled feedstock to a fully operational heavy rare earth separation (and the downstream magnet manufacturing) is substantial. Key issues:

• The 4% Dy+Tb in SEG+ is a positive start, but it requires significant volume, processing yield, and qualification to translate into magnet-grade output.
• MP’s own communications suggest magnet manufacturing and HREE separation are “under development” rather than fully commercial at scale.
• The DoD-driven schedule shows commissioning by “mid-2026” for heavy-rare-earth separation. That pushes beyond “next year.”

In a messaging communication, MP Materials’ Matthew Sloustcher, Chief Communications Officer, shared with REEx.

We announced yesterday (link below) that we plan to begin commissioning our HREE refinery in mid-2026, targeting 200mtpa capacity for Dy/Tb. We also noted that this supports our goal of 10,000mt of NdFeB magnet production capacity. Note that grain-boundary-diffusion (GBD) and other thrifting technologies are reducing HREE intensity in high-performance magnets, and not all applications require HREEs—but we believe our approach remains well-aligned with market needs.As mentioned in the update, we’ll be processing our own SEG+ material, which we've been producing and stockpiling since late 2023, building up inventory (on an REO basis, it already amounts to hundreds of tons of SEG+). We also plan to incorporate third-party feedstocks and are actively engaged in discussions with several sources, expecting to integrate multiple over time.

Additionally, the recycling facility we're building to support our Apple partnership will provide recycled feedstocks that include both LREEs and HREEs.

Positive Signals

MP Materials continues to position itself as the cornerstone of America’s rare-earth revival. Management reaffirmed that commissioning of its HREE refinery is set for mid-2026, targeting 200 metric tons per year of dysprosium and terbium—enough to anchor a 10,000 MT NdFeB magnet capacity in Texas.  An aggressive but, according to company management, achievable goal.

The company emphasized that new thrifting and GBD technologies are lowering HREE intensity across magnet designs, giving MP valuable flexibility as it scales. Executives said the firm is already stockpiling hundreds of tons of SEG+ feedstock produced at Mountain Pass since 2023 and intends to process both this internal material and third-party feedstocks under active negotiation.

In parallel, a new recycling facility tied to MP’s Apple partnership will soon recover both light and heavy REEs from end-of-life magnets—creating a closed-loop domestic supply. These moves underscore MP Materials’ claim that it is not merely building a mine-to-magnet chain, but a self-sustaining ecosystem of rare-earth production, refining, and recycling on U.S. soil—an ambitious yet credible foundation for true supply-chain independence.

Feedstock Source? What About A Missouri wildcard: Pea Ridge Mine?

While MP is working through California, another potential heavy-rare-earth feedstock sits in Missouri. The Pea Ridge iron-oxide-apatite deposit (opens in a new tab) in Washington County contains breccia pipes enriched in REEs, including dysprosium and terbium. Research notes total REE oxide (REO) content in breccia-pipe samples averaging ~20 wt% (undiluted) and significant heavy-rare-earth presence (opens in a new tab). The owner, Caldera Holding LLC, holds the mine and has purportedly licensed commercial separation technology.

This site offers a compelling feedstock alternative — and if it can deliver, it could significantly bolster MP’s chain, either through feedstock supply or easing the Dy/Tb shortage. But it remains a potential, not a guaranteed supply. A lot will depend on any remaining permitting, separation demonstration, and mine redevelopment timelines. REEx is planning a visit to the mine in December.

Bottom Line—Supportive and Caution

MP Materials is making the right moves — owning the mine, creating feedstock (SEG+), clinching government (and financial) backing, and planning downstream magnet manufacture.  Also, the heavy rare-earth piece is not yet fully in hand. The “next-year” capability to produce sufficient Dy and Tb in volume remains optimistic based on the complex world of REEs.  Yet, MP Materials has certainly been known to execute over the past few years.   And the C-suite is expressing confidence.

REEx suggests that the existence of Pea Ridge offers a possible boost, yet relying on it within MP’s timeframe could pose a risk too.

Time is of the essence

The U.S. supply-chain gap for HREEs is real; China still dominates the separation and refining of Dy/Tb. The strategic opportunity is real — MP Materials remains America’s best shot. But to deliver, it will need both high-volume rare-earth materials and refined magnet output, and it will need them fast. The 10X vision remains alive — but it must now be executed with precision, transparency, and urgency. And in parallel, why not consider other sources of DyTb, especially domestic, such as Pea Ridge Mine?

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