Resolution Minerals Ltd (ASX:RML, OTC:RLMLF) has begun a large-scale stream sediment sampling program at its Horse Heaven antimony-gold-silver-tungsten project in central Idaho, United States. The work marks the first modern, district-wide geochemical survey on the ground and is aimed at opening up new exploration fronts beyond the project’s known prospects.
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Location plan of the Horse Heaven Project. Note that the coordinates are in metres north and east metric system (not latitude/longitude) centric to this part of North America.
The program will cover about 59 square kilometres and roughly 44 kilometres of streams, with an estimated 100 samples to be collected. Field crews will focus on multiple catchments draining prospective structures outside the better-understood Golden Gate and Antimony Ridge targets.
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Map of planned soil sediment sampling program to be undertaken at the Horse Heaven Project.
Testing the IRGS model and buried intrusion
Resolution is targeting mineralisation linked to an interpreted buried intrusion between Horse Heaven and Perpetua Resources’ adjacent Stibnite Gold Project, a region that has seen little systematic modern exploration. Company geologists believe the area is prospective for antimony, tungsten, gold and silver and intend to use the new geochemical data to pinpoint anomalies for follow-up soil grids, geophysical surveys and potential drill programs.
A key objective is to test the validity of the Intrusion Related Gold System (IRGS) model at Horse Heaven and confirm its relationship to the Stibnite deposit. Stibnite, owned by Nasdaq-listed Perpetua (PPTA.NAS), hosts a 4.8-million-ounce gold reserve and significant antimony and tungsten resources. Perpetua has successfully employed similar stream-sediment techniques to define drill targets at its project.
“I believe Horse Heaven has the scale to be a district play and is one of the most target-rich projects I have ever been associated with,” said RML’s CEO of US operations, Craig Lindsay.
“It’s very exciting to have a project that comprises past production, historical resources and significant district-scale exploration potential with exposure to critical metals, including antimony, tungsten, silver and gold,” he added.
Strategic context for critical minerals
The US is currently 100% import-reliant on antimony, a critical element used in ammunition, flame retardants and renewable technologies, underlining the potential strategic significance of Horse Heaven if advanced to development and production. Interest in the region is already high: senior US officials, including Idaho Governor Brad Little and US Army Major General John Reim, recently visited the Stibnite site as Perpetua secured development approvals.
Perpetua has also attracted substantial funding support. In September 2025 it announced initial terms for a US$2 billion loan from the Export-Import Bank of the United States, which would almost fully fund the restart of Stibnite — once America’s last domestic source of antimony before its 1990s closure. In June 2025 Perpetua raised US$425 million from banks and investors, including a US$100 million injection from Paulson & Co., to advance the project.
Next Steps
Resolution expects results from its stream-sediment program to shape the next phase of exploration at Horse Heaven, which could include mapping, soil sampling grids, ground geophysical work and drill testing. By rapidly expanding geochemical coverage over a materially underexplored area, the company aims to generate fresh, high-priority targets in a district that may play a growing role in North America’s supply of critical minerals.