American Rare Earths lifts resource for Cowboy State

A resource update for American Rare Earths’ (ASX: ARR) Cowboy State mine (CSM) area, part of its main Halleck Creek project in Wyoming, boosted the tonnage by 12% over the previous estimate from February. 

The updated indicated resource for CSM now totals 391.3 million tonnes grading 3,295 parts per million (ppm) total rare earth oxides (TREO) for 1.28 million tonnes contained TREO, the company reported Wednesday. Inferred resources declined 29% to 156 million tonnes in the update, at 3,468 ppm for 541,251 tonnes contained TREO. 

American Rare Earths’ subsidiary, Wyoming Rare, holds the Halleck Creek project, which was named in 2023 as one of the world’s top 10 rare earth projects measured by TREO. 

New drill permits

The update incorporates the results from 18 additional channel samples and coincides with the acquisition of two new exploration drilling permits. The channel sample results enabled reclassification of about 63.9 million tonnes to the indicated category from the inferred category from the estimate in the February 2025 updated CSM Scoping Study. 

Additional mapping associated with channel sampling expanded the resource area to increase the CSM mineral resource estimate by approximately 4.5 million tonnes, ARR said.  

Last month, ARR received two drilling permits from the Wyoming Department of Environmental Quality and 27 drill hole locations were permitted across the CSM area in preparation for in-fill drilling required for future technical studies beyond the forthcoming prefeasibility study, the company noted.

Last year, Cowboy State mine was approved for up to $7.1 million in state-backed non-dilutive funding through a grant. 

The funding agreement was reached with support from the Wyoming Energy Authority and the University of Wyoming Energy Resources Council with the mission to support projects to advance the state’s energy economy. 

Australian-headquartered ARR shares closed the day down 3% to A41¢ in Sydney, for A$243.5 million ($156.8 million) market capitalization.