American Rare Earths Commences 2026 Drilling at Halleck Creek to Underpin Feasibility Study

Rhea-AI Summary

American Rare Earths (ADR: AMRRY) has started its 2026 exploration drilling program at the Cowboy State Mine within the Halleck Creek project in Wyoming. The program underpins a Definitive Feasibility Study at what is described as one of the largest US rare earth deposits on a TREO basis.

The campaign plans up to 3,050 meters of HQ core across 19 holes, generating about 1,045 core samples for assays and extensive geotechnical, hydrological, environmental and metallurgical test work. Drilling began May 13, 2026, and is scheduled to finish by mid-July.

Positive

• Up to 3,050 meters of HQ core drilling across 19 holes at Cowboy State Mine
• Program designed to support a Definitive Feasibility Study for Halleck Creek
• Approximately 1,045 core samples expected for assay and additional test work
• Nine holes target higher-grade zones planned for first five years of mining
• Ten holes aim to delineate additional higher-grade mineralization around Red Mountain base
• Drilling scheduled from May 13, 2026 to mid-July, providing near-term data flow

Negative

• None.

News Market Reaction – AMRRY

+0.99%

+0.99% Session close to close

In the May 27 session, AMRRY gained 0.99%, reflecting a mild positive market reaction.

Data tracked by StockTitan Argus on the day of publication.

Market Context

This announcement outlines a feasibility-stage drilling program at Halleck Creek, with up to 3,050 m...

Analysis

This announcement outlines a feasibility-stage drilling program at Halleck Creek, with up to 3,050 meters across 19 holes and about 1,045 core samples to support a Definitive Feasibility Study. It follows recent work on pilot plants and property-wide planning, reinforcing a consistent de-risking strategy. Investors may watch for resource classification upgrades, geotechnical results for mine design, and how this work ties into previously disclosed large-scale metrics such as contained TREO and projected mine life.

Key Figures

Planned drilling length: 3,050 meters Planned drill holes: 19 holes Core samples: 1,045 samples +5 more

8 metrics

Planned drilling length 3,050 meters 2026 exploration drilling program at Cowboy State Mine

Planned drill holes 19 holes HQ core on Red Mountain at Cowboy State Mine

Core samples 1,045 samples Expected assay samples from 2026 drilling campaign

Average hole depth 125 meters Typical depth for planned core holes

Deeper hole range 200–300 meters Selected holes testing deeper mineralization

Resource tonnage 2.63 billion tonnes In-situ tonnage at Halleck Creek project (prior WPDA release)

Contained TREO 8.64 million tonnes Estimated contained Total Rare Earth Oxide at Halleck Creek

Mine life 20-year Approximate mine life for Cowboy State in prior study

Historical Context

5 past events · Latest: Apr 28 (Positive)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Apr 28	Leadership appointments	Positive	-0.7%	Added Wyoming-focused public affairs and project engineering leadership for Halleck Creek.
Apr 09	Pilot plant pathway	Positive	-0.8%	Outlined three-stage pilot plant to accelerate pre-production rare earth oxide output.
Apr 07	Development assessment	Positive	-1.7%	Awarded whole-of-property assessment to integrate geology, mining and permitting plans.
Apr 01	Pilot plant acceleration	Positive	+1.7%	Accelerated pilot plant using test work showing strong gangue rejection and TREO recovery.
Mar 30	Oxide-to-metal study	Positive	+4.5%	Engaged Tetra Tech for an Oxides to Metals study on heavy rare earths stream.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

Across five generally constructive Halleck Creek updates, three saw negative 24-hour price reactions and two saw gains, indicating investors have often faded positive project news in the short term.

Recent Company History

Over the past few months, American Rare Earths has consistently advanced the Halleck Creek project. On Mar 30, 2026, it commissioned an Oxides to Metals study, followed by accelerating a pilot plant on Apr 1 and launching a Whole of Property Development Assessment on Apr 7. Subsequent announcements on a pilot plant pathway and Wyoming leadership hires in April focused on execution and permitting. This new feasibility-level drilling campaign fits into that sequence as another step in de-risking and progressing Halleck Creek towards potential production.

Key Terms

total rare earth oxide, definitive feasibility study, pre-feasibility study, ore reserve, +3 more

7 terms

total rare earth oxide technical

"largest known rare earth deposit in the United States on a total rare earth oxide (TREO) basis"

Total rare earth oxide (TREO) is the combined percentage of all rare earth elements in a mineral sample, reported as if each element were its oxide form; it’s the standard way miners and buyers state how much valuable material is present. Investors watch TREO because higher percentages mean a richer, more marketable deposit or concentrate—like knowing the sugar content tells you how sweet a fruit—affecting potential revenue, processing costs and product value.

definitive feasibility study technical

"foundation for a Definitive Feasibility Study (DFS)"

A definitive feasibility study is a detailed, near-final assessment that shows whether a proposed project—often a mine, infrastructure or major industrial venture—can be built and operated profitably. It combines precise engineering plans, realistic cost estimates, production schedules and risk analysis to give lenders and investors a clear picture of expected returns and potential pitfalls, like a full blueprint and budget that helps decide whether to greenlight financing and construction.

pre-feasibility study technical

"reviewing and optimizing the Pre-Feasibility Study, we are moving ahead"

A pre-feasibility study is an initial assessment that evaluates whether a proposed project or investment idea is worth exploring further. It involves examining basic factors like costs, potential benefits, and possible challenges, similar to conducting a preliminary check before deciding to invest more time and resources. This helps investors determine if pursuing the project further is practical and likely to be successful.

ore reserve technical

"These holes are designed to support potential future ore reserve estimation"

An ore reserve is the portion of a mineral deposit that has been tested and judged to be economically and technically feasible to extract under current conditions, meaning it can be mined profitably. For investors it matters because reserves represent the mineable asset base—like the usable fuel in a tank—and determine a mine’s potential revenue, operational life and risk profile, so changes in reserves can materially affect a company’s value.

measured and indicated technical

"conversion of a majority of tonnes ... to Measured and Indicated classifications"

Measured and indicated are two levels of confidence used to describe the size and quality of a mineral deposit: "measured" means the quantities and grade are well tested and closely known, while "indicated" means they are reasonably estimated but with more uncertainty. Investors use these categories to judge how reliably a resource can be converted into reserves and future cash flow—think of measured like a weighed recipe and indicated like a good estimate based on past batches.

geomechanical technical

"support detailed geomechanical analysis for mine design"

Relating to the mechanical behavior of earth materials like rock, soil and the forces that act on them, geomechanical describes studies and measurements used to predict how the ground will respond to activities such as drilling, mining, tunneling or reservoir fluid changes. For investors, geomechanical assessments matter because they influence project safety, engineering costs, production rates and the risk of delays or environmental incidents—think of it as testing whether the ground will hold up under planned operations.

hydrogeological technical

"material for hydrogeological and baseline environmental studies"

Relating to the distribution and movement of groundwater beneath the surface and the properties of the soils and rocks that hold or transmit that water. For investors, hydrogeological information matters because it affects water supply, pollution risks, construction foundations, mining and energy projects, and cleanup costs — think of it as the earth’s plumbing system that can make projects work smoothly or create costly surprises.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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DENVER, May 27, 2026 (GLOBE NEWSWIRE) -- American Rare Earths (ASX: ARR | OTCQX: ARRNF | ADR: AMRRY) (“ARR” or the “Company”) is pleased to announce that the 2026 exploration drilling program has commenced at the Cowboy State Mine (“CSM”) within the Halleck Creek Rare Earths Project in Wyoming. The program marks the start of feasibility-level drilling at what is believed to be the largest known rare earth deposit in the United States on a total rare earth oxide (TREO) basis¹, and is designed to provide the geological and geotechnical foundation for a Definitive Feasibility Study (DFS).

“Commencing this drilling program is an important and exciting step as we continue to accelerate Halleck Creek,” said Mark Wall, CEO of American Rare Earths. “While we are actively reviewing and optimizing the Pre-Feasibility Study, we are moving ahead in parallel with feasibility-stage drilling so that we do not lose time. This campaign is one of several workstreams underway to advance what we believe is the largest domestic rare earths project in the United States, on a TREO basis, towards production.”

Program summary

ARR has engaged Boart Longyear to drill up to approximately 3,050 meters (10,000 feet) of HQ core across 19 holes on Red Mountain at the CSM. Dahrouge Geological Consulting has been retained to manage the exploration program and to provide on-site geological logging and sample preparation services for the duration of the campaign.

Drilling commenced on May 13, 2026, and is scheduled to conclude by mid-July. The program is expected to generate roughly 1,045 core samples for assay, with remaining core retained for further geotechnical, hydrological, environmental and metallurgical testwork. All holes will be geophysically logged, including optical and/or acoustic televiewer surveys, to support detailed geomechanical analysis for mine design.

Resource and feasibility objectives

Nine of the proposed core holes are located on the top of Red Mountain, targeting higher-grade zones within the first five years of planned mining as outlined in the CSM pre-feasibility study pit shells. These holes are designed to support potential future ore reserve estimation as part of the DFS.

A further ten core holes will be drilled around the base of Red Mountain to delineate additional higher-grade mineralization identified through previous channel sampling and recent geological mapping. Collectively, the program aims to:

• Upgrade the current resource, targeting conversion of a majority of tonnes within planned early-mining phases to Measured and Indicated classifications
• Test extensions of the mineralization at depth and to the west of existing drilling
• Provide core for geomechanical testing, informing pit slope design and mine planning
• Generate material for hydrogeological and baseline environmental studies
• Supply additional samples for metallurgical test work to further de-risk and optimize the processing flowsheet
  

Operational details

Approximately twelve of the nineteen planned holes will be drilled from platforms constructed on outcrop near the crest of Red Mountain, Figure 2. Due to the rugged terrain, helicopter support will be used to transport platform materials, the drill, and core boxes to and from these sites, Figure 1. Average hole depth is expected to be approximately 125 meters, with selected holes extending to 200–300 meters to test deeper mineralization.

On site, core will be photographed, logged and split by field geologists before being dispatched to ALS Global for assay, Figure 3. Residual core will be stored for future confirmatory or specialized testing as required during the DFS.

Figure 1- Exploration Staging Area

Figure 2- Proposed Hole Locations

Figure 3- Core from initial drill hole location PL5-RM-005
 

This release was authorized by the Board of American Rare Earths.

About American Rare Earths Limited:

American Rare Earths (ASX: ARR | OTCQX: ARRNF | ADR: AMRRY) is a critical minerals company at the forefront of reshaping the U.S. rare earths industry. Through its wholly owned subsidiary, Wyoming Rare (USA) Inc. (“WRI”), the company is advancing the Halleck Creek Project in Wyoming—a world-class rare earth deposit with the potential to secure America’s critical mineral independence for generations. Located on Wyoming State land, the Cowboy State Mine within Halleck Creek offers cost-efficient open-pit mining methods and benefits from streamlined permitting processes in this mining-friendly state.

With plans for onsite mineral processing and separation facilities, Halleck Creek is strategically positioned to reduce U.S. reliance on imports—predominantly from China—while meeting the growing demand for rare earth elements essential to defense, advanced technologies, and economic security. As exploration progresses, the project’s untapped potential on both State and Federal lands further reinforces its significance as a cornerstone of U.S. supply chain security. In addition to its resource potential, American Rare Earths is committed to environmentally responsible mining practices and continues to collaborate with U.S. Government-supported R&D programs to develop innovative extraction and processing technologies for rare earth elements.

Investors can follow the Company’s progress at www.americanree.com

For more information:

Nick Lissolo, Vice President, Corporate Development and Strategy
nlissolo@americanree.com 

Media Contact:

Susan Assadi
sassadi@americanree.com
347 977 7125

Investor Relations US Contact:

Beverly Jedynak
Beverly.jedynak@viriathus.com
312 943 1123

¹ Refer ASX announcement dated 4 February 2025

Photos accompanying this announcement are available at
https://www.globenewswire.com/NewsRoom/AttachmentNg/54b78834-534c-45a3-aaf7-24d7241af0e2
https://www.globenewswire.com/NewsRoom/AttachmentNg/63bbe8d6-f90f-4415-9764-0dcb1e35f30a
https://www.globenewswire.com/NewsRoom/AttachmentNg/be6e46f8-5913-4a5e-9a77-68815e182c5a

FAQ

What is American Rare Earths (AMRRY) 2026 drilling program at Halleck Creek?

American Rare Earths has launched a 2026 exploration drilling campaign at the Cowboy State Mine within its Halleck Creek rare earths project in Wyoming. According to American Rare Earths, this feasibility-level program supports a Definitive Feasibility Study and future mine design, testing and permitting work.

How many drill holes and meters are planned in American Rare Earths (AMRRY) 2026 program?

The 2026 program plans up to 3,050 meters (10,000 feet) of HQ core drilling across 19 holes on Red Mountain at Cowboy State Mine. According to American Rare Earths, average depth is about 125 meters, with select holes extending to 200–300 meters.

When did American Rare Earths (AMRRY) start the 2026 Halleck Creek drilling and when will it end?

Drilling at Halleck Creek commenced on May 13, 2026, and is scheduled to conclude by mid-July 2026. According to American Rare Earths, this timeline allows sufficient time to collect core, complete logging, and begin assays and technical studies for the Definitive Feasibility Study.

What are the main objectives of American Rare Earths (AMRRY) 2026 drilling at Cowboy State Mine?

The program aims to upgrade resources, test mineralization extensions, and generate data for mine design and processing optimization. According to American Rare Earths, goals include converting early-mining tonnes to Measured and Indicated and supplying samples for geotechnical, hydrogeological, environmental and metallurgical work.

How will the 2026 drilling support the Halleck Creek Definitive Feasibility Study for American Rare Earths (AMRRY)?

The drilling provides core and data required for feasibility-level resource classification, geomechanical analysis, and processing test work. According to American Rare Earths, results will inform ore reserve estimation, pit slope design, hydrogeological studies, environmental baselines and optimization of the processing flowsheet.

Which zones are targeted by American Rare Earths (AMRRY) 2026 drilling at Red Mountain?

Nine planned core holes target higher-grade zones on top of Red Mountain within the first five years of planned mining. According to American Rare Earths, ten additional holes around the base test higher-grade mineralization identified by earlier channel sampling and mapping.