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
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 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 10, 2026, that it had further defined the pilot plant execution plan, with the initial processing stages to be undertaken in Wyoming, and the final hydrometallurgical processing and oxide refining stage to be completed in Saskatchewan, Canada.

The pilot programme has been structured in three stages: milling and sizing; mineral separation and concentration; and leaching, impurity removal and oxide refining. Milling and sizing will be undertaken by the Western Research Institute in Laramie, Wyoming, while mineral separation and concentration will be undertaken at DISA Technologies’ facility in Casper, Wyoming. The final stage will be completed by the Saskatchewan Research Council in Saskatoon.

AAR said ore already extracted from the Halleck Creek site and stockpiled in Laramie would be used for the pilot plant. 

The final stage will be engineered by SRC and Tetra Tech on the basis of the prefeasibility study flowsheet; pilot campaign data will be used to support the design criteria for the commercial plant and mine.

Key Contracts, Suppliers and Consultants
Jaye Pickarts (pilot plant process lead and metallurgical engineering consultant); Western Research Institute (milling and sizing); DISA Technologies (mineral separation and concentration); Saskatchewan Research Council (leaching, impurity removal and oxide refining); and Tetra Tech (engineering support for the final pilot plant stage).

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