American Rare Earths Ltd (ASX:ARR, OTCQB:ARRNF) successfully produced Mixed Rare Earths Oxide (MREO) from Halleck Creek ore using its updated mineral processing flowsheet during the December 2025 quarter, describing the result as a key technical milestone.
The quarter’s work advanced multiple technical streams across metallurgical processing, beneficiation optimisation and resource definition, alongside corporate leadership changes.
ARR said the oxide was produced from purified pregnant leach solution via precipitation of a mixed rare earth oxalate, followed by calcining to generate the MREO product.
The company linked the outcome to impurity-removal neutralisation testwork completed earlier in the quarter, which it said addressed historical processing challenges associated with allanite-hosted rare earth mineralisation and supported continuity across its hydrometallurgical evaluation program.
Beneficiation optimisation and updated preliminary flowsheet
ARR reported beneficiation optimisation activities progressed during the quarter, with initial results released alongside an updated mineral processing flowsheet.
It said the flowsheet integrates recent testwork outcomes and remains preliminary, with further optimisation and evaluation planned as part of ongoing technical studies.
Cowboy State Mine: Updated MRE underpins technical studies
The company completed an updated Mineral Resource Estimate for the Cowboy State Mine area within the Halleck Creek project during the quarter.
ARR said the update provides an improved geological foundation for ongoing technical workstreams and reclassified indicated resources by 68.4Mt.
Leadership and partnerships: CEO appointment and US funding focus
ARR appointed Mark Wall as CEO, citing more than 30 years’ global mining experience across project development, permitting, construction and operations.
The company also expanded its relationship with Tetra Tech to support work assessing US government funding opportunities aimed at developing mine-to-magnet capabilities in the United States.
Meanwhile, the University of Wyoming School of Energy Resources, in partnership with Wyoming Rare (USA) Inc., was awarded a Seed Translational Acceleration of Research (STAR) project under an NSF-funded program.
The project is intended to advance applied research into potential byproducts from rare earth extraction at Halleck Creek, including a material properties database, modelling of potential uses and laboratory validation of applications, with ARR noting benign byproducts could have positive economic implications if industrial uses are identified.
Outlook: PFS integration, permitting and drilling preparation
For the March 2026 quarter, ARR outlined priorities including integration of metallurgical and beneficiation results into its Halleck Creek prefeasibility study, planning for demonstration plant alternatives to validate the flowsheet at scale, and continued environmental baseline studies and hydrological modelling to support the Wyoming Department of Environmental Quality permit-to-mine application.
The company also flagged preparations for infill drilling across 27 permitted drill holes at Cowboy State Mine to lift geological confidence and support future studies.
Cash position: $23.98 million at quarter end
At December 31, 2025, ARR reported cash of A$23.98 million and financial assets of A$2.4 million associated with ASX-listed Cobalt Blue Holdings and Godolphin Resources.
ARR said it received the final A$1 million payment (plus accrued interest) from Cobalt Blue under a promissory note, and raised a further A$4.5 million through the exercise of 11.6 million options in October and November 2025.
Subsequent to quarter end, ARR completed the sale of its Godolphin shareholding for proceeds of A$2.89 million.