American Rare Earths Hits 3,497ppm Average Grade Across First Six Feasibility Holes
Key Takeaways
- The first six holes of ARR's 2026 Feasibility Study drilling program returned a pooled average of 3,497 ppm TREO and a median of 3,879 ppm TREO across 386 geological assay intervals at the Cowboy State Mine, Halleck Creek.
- 93% of sampled intervals (358 of 386) exceed the 1,000 ppm TREO resource cut-off grade, confirming pervasive rather than patchy mineralisation across the drill program.
- HC26-RM056 delivered 191 metres of continuous mineralisation at a weighted average of 3,951 ppm TREO — the kind of broad, consistent interval that underpins reliable open-pit mine planning.
- The magnet rare earth oxide (MREO) fraction averages 981 ppm across all intervals, with neodymium (Nd₂O₃) at 622 ppm and praseodymium (Pr₆O₁₁) at 205 ppm — directly aligned with ARR's NdPr oxide commercial strategy targeting U.S. defence and energy-transition customers.
- Twelve of the 18 completed holes are yet to report assays, with results expected over coming weeks, representing near-term catalysts for the ongoing Feasibility Study program.
Strong opening assay results validate Cowboy State Mine’s geological model
American Rare Earths has received the first certified assay results from its 2026 Feasibility Study drilling program at the Cowboy State Mine, Red Mountain, Halleck Creek Rare Earths Project in Wyoming. The headline numbers are compelling: a pooled average grade of 3,497 ppm TREO (Total Rare Earth Oxide) and a median of 3,879 ppm TREO across 386 unique geological assay intervals from six HQ core holes.
Approximately 93% of sampled intervals (358 of 386) exceed the company’s 1,000 ppm TREO resource cut-off grade. The peak result of 9,084 ppm TREO over 3.02 metres came from hole HC26-RM051, while HC26-RM056 delivered 191 metres of continuous mineralisation at a weighted average of 3,951 ppm TREO.
These are the first results from an 18-hole program. Assay results from the remaining 12 holes are expected over the coming weeks.
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Initial six holes by the numbers
The table below summarises per-hole highlights from Table 1 of the announcement. All figures are in ppm unless noted; reported intervals are downhole lengths, and true widths are not known.
| Drill Hole | Reported Interval (m) | TREO Mean (ppm) | TREO Max (ppm) | MREO Mean (ppm) |
|---|---|---|---|---|
| HC26-RM051 | 128.0 | 3,469 | 9,084 | 995 |
| HC26-RM052 | 116.7 | 3,347 | 5,268 | 934 |
| HC26-RM053 | 119.3 | 3,046 | 7,717 | 855 |
| HC26-RM054 | 118.0 | 3,553 | 4,836 | 997 |
| HC26-RM055 | 117.9 | 3,744 | 5,382 | 1,045 |
| HC26-RM056 | 189.3 | 3,726 | 6,939 | 1,038 |
| Pooled Average | 789.2 (total) | 3,497 | 9,084 | 981 |
Two results stand out in particular:
- HC26-RM056 returned a significant mineralised interval of 191.11 metres from 8.84 m to 199.95 m at a weighted average of 3,951 ppm TREO. For an open-pit mine, broad continuous intervals like this reduce strip-ratio risk and underpin more predictable mining unit grades across large bench areas.
- HC26-RM051 delivered the program’s peak single-sample assay of 9,084 ppm TREO over 3.02 metres, confirming higher-grade pockets exist within the broader mineralised envelope.
What rare earth grades mean for investors — and why continuity matters
TREO stands for Total Rare Earth Oxide, the standard metric for expressing the combined concentration of all rare earth elements in oxide form. It is the headline grade number you will see in most project comparisons. Within TREO, there are three sub-categories that matter to investors:
- LREO (Light Rare Earth Oxide): The most abundant fraction, dominated by lanthanum and cerium. Lower value but present in large tonnages.
- MREO (Magnet Rare Earth Oxide): Comprises Pr₆O₁₁, Nd₂O₃, Sm₂O₃, Tb₄O₇, and Dy₂O₃. This is the commercially critical fraction that feeds permanent magnet supply chains used in EV motors, wind turbines, and defence systems.
- HREO (Heavy Rare Earth Oxide): Includes yttrium and heavier elements. Strategic in defence and high-performance applications.
Across the 386 intervals, MREO averages 981 ppm. The MREO distribution from Figure 1 of the announcement breaks down as: Nd₂O₃ at 622 ppm; Pr₆O₁₁ at 205 ppm; Sm₂O₃ at 102 ppm; Tb₄O₇ at 10 ppm; and Dy₂O₃ at 47 ppm. ARR’s stated strategy is to supply NdPr oxide and strategic heavy rare earths to U.S. defence, energy-transition, and advanced-manufacturing customers, making the MREO composition directly relevant to the company’s commercial pathway.
The 1,000 ppm TREO cut-off is the threshold ARR applies to the current Cowboy State Mine Mineral Resource. Grades above this level are considered economically extractable under the resource model assumptions. The fact that 93% of intervals clear this bar is not a marginal result — it demonstrates the mineralisation is pervasive rather than patchy.
For an open-pit mine, continuity is arguably as important as peak grade. Isolated high-grade zones can be difficult to mine selectively and may require blending with lower-grade material. Broad, continuous mineralisation across 117 to 191 metres of downhole length is the kind of geological consistency that mine planners need to build reliable production schedules.
Results consistent with the Cowboy State Mine resource — and what comes next
Drilling confirms geological model continuity
The 2026 program is not greenfields exploration. These are infill and confidence-upgrade holes drilled on centres consistent with the existing Mineral Resource drilling program at Red Mountain. All six holes confirmed broad, near-surface mineralisation consistent with the allanite-hosted rare earth system already represented in the JORC Mineral Resource Estimate.
For context, the total Halleck Creek JORC Mineral Resource Estimate stands at 2.63 billion tonnes at 3,292 ppm TREO for 8.65 million tonnes of contained rare earth oxides (per the ASX announcement dated 4 February 2025). The Cowboy State Mine sub-resource, at a 1,000 ppm TREO cut-off, is 547.5 Mt (per the ASX release dated 19 November 2025). The first-tranche drilling results sit comfortably within the grade range represented by that existing resource, adding geological confidence rather than introducing any new discovery claim.
Program scope and next steps
The full 2026 drilling program comprises up to approximately 2,877 metres of HQ core across 18 holes on Red Mountain, drilled by Boart Longyear, with Dahrouge Geological Consulting managing on-site logging and sample preparation. A total of 18 holes were completed, one fewer than the 19 originally planned, following a mechanical issue with the drill rig during the final stages. Twelve of the 18 completed holes target higher-grade zones near the top of Red Mountain, within areas associated with the early conceptual mining sequence for the Cowboy State Mine.
The forward work programme includes:
- Certified assay results from the remaining 12 holes, reported as laboratory processing and QA/QC review are completed
- Ongoing geological modelling and lithological interpretation integrating 2026 drilling with the existing Cowboy State Mine geological model
- Evaluation of Mineral Resource classification within areas relevant to the proposed early mining sequence
- Progression of the Whole of Property Development Assessment (WPDA)
- Future Mineral Resource updates where appropriate
Management perspective
CEO Mark Wall focused his commentary on the grade metrics delivered by the first six holes:
Mark Wall, Chief Executive Officer, American Rare Earths
“These first assays, from just the initial six of eighteen planned holes, are an encouraging start to the 2026 program. Approximately 93% of the reported samples exceed our 1,000 ppm TREO resource cut-off, with an average grade of 3,497 ppm TREO and a median grade of 3,879 ppm TREO. Just as importantly, we are seeing broad continuous mineralization across the initial holes, including 191 metres at 3,951 ppm TREO in HC26-RM056. With the balance of the program still to be reported, these results provide important additional data to support the geological model and ongoing Feasibility Study work at the Cowboy State Mine.”
Chief Development Officer Andrew Conover highlighted what the results mean for the geological model and Feasibility Study execution:
Andrew Conover, Chief Development Officer, American Rare Earths
“From a project execution standpoint, what stands out in this first tranche is the consistency and continuity of the mineralization. The drilling has returned broad mineralized intervals rather than isolated high-grade zones. That is an important characteristic as we continue to refine the geological model and advance the technical work supporting the Cowboy State Mine Feasibility Study.”
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Investment case: why this matters for ARR
The first-tranche results from the 2026 Feasibility Study drilling program do meaningful work for ARR’s project development narrative. Broad, consistent grades in the initial six holes reduce geological risk in the mine model and support the Mineral Resource classification work that underpins any future mine plan.
ARR is advancing toward a domestic mine-to-oxide platform targeting U.S. critical minerals demand, with NdPr oxide and strategic heavy rare earths as the commercial focus. The assay data released to date is consistent with that strategy, demonstrating that the grades necessary to support the Cowboy State Mine concept are present and continuous across meaningful downhole intervals.
With 12 holes still to report, there are near-term catalysts remaining in this program. Investors should note, however, that these are Exploration Results supporting a Feasibility Study, not Ore Reserves. The referenced Scoping Study is a Class 5 AACE (±25–35%) preliminary assessment and does not provide assurance of an economic development case. Actual results as the Feasibility Study progresses may differ materially from preliminary assessments.
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