Name of the Project
Halleck Creek rare earths project.

Location
Central Laramie Mountains, Wyoming, US.

Project Owner/s
Wyoming Rare (USA) Inc (WRI), a subsidiary of American Rare Earths (AAR).
 
Project Description
An updated 2025 scoping study shows Halleck Creek has a Joint Ore Reserves Committee-compliant resource of 2.63-billion tonnes grading 3 292 parts per million (ppm) total rare-earth oxides (TREOs). 

The project comprises the Cowboy State mine in American Rare Earths’ southern land holdings and the Overton mountain resource area in the north.

It is planned that project will be developed in two phases. Phase 1 is the Cowboy State mine, which has a 20-year life-of-mine (LoM) and a three-million-tonne-a-year base-case processing rate. Phase 2 would involve the broader Halleck Creek development on federal land and minerals, with a potential mine life of more than 80 years. 

Under the Phase 1 base case, average neodymium/praseodymium equivalent production is estimated at 2 790 t/y over the LoM. 

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
Under the three-million-tonne-a-year base case for the Cowboy State mine, the updated scoping study indicates an after-tax tax net present value, at a 10% discount rate, of $558-million and an internal rate of return of about 24%. 

Capital Expenditure
Initial capital expenditure for the Cowboy State mine is estimated at $456-million, including contingency. 

Planned Start/End Date
Construction is expected to take 2.5 years to complete.

Latest Developments
AAR reported on April 2, 2026, that it had made rapid progress on its pilot programme to produce preproduction rare earths concentrate from Halleck Creek. 

The pilot plant process is being led by metallurgical engineer Jaye Pickarts, and three key front-end processing units — two induced roll magnetic separators and a reflux classifier — are being fabricated on an expedited schedule.

The remainder of the pilot circuit will use conventional processing equipment, allowing the team to focus on integrating and optimising the critical-path units. Early testwork on the circuit indicated TREO recovery of about 70% and grade enrichment of about ten times relative to feed.

AAR holds a permit to mine up to 60 000 t of ore for testing and has already mined about 3 100 t of Halleck Creek material to feed the pilot plant. The ore is intended to produce representative preproduction concentrates for metallurgical validation, downstream processing testwork and discussions with potential offtakers. 

Key Contracts, Suppliers and Consultants
Jaye Pickarts (pilot plant process lead and metallurgical engineering consultant) 

Contact Details for Project Information
American Rare Earths, tel +61 2 8054 9779 or email info@americanree.com.