Resolution Minerals Ltd (ASX:RML, OTC:RLMLF) has reported new high-grade antimony, silver and gold assays from rock sampling at the historical Antimony Ridge Mine within its Horse Heaven Project in Idaho, USA.
Results from five massive stibnite samples collected in October 2025 confirmed “widespread” high-grade antimony mineralisation, with peak grades including 48.7% Sb and 270 g/t Ag (sample 732005) and 37.9% Sb and 890 g/t Ag (sample 732008).
Antimony Ridge sits immediately adjacent to Perpetua Resources’ Stibnite Gold Project, an antimony-gold development in Idaho.
Key assays (grab samples)
Resolution reported the following results from the five stibnite samples collected from within historical open pits and trenches:
- 732005: 48.7% Sb, 270 g/t Ag and 0.69 g/t Au
- 732006: 35.5% Sb, 223 g/t Ag and 1.07 g/t Au
- 732007: 42.0% Sb, 200 g/t Ag and 0.85 g/t Au
- 732008: 37.9% Sb, 890 g/t Ag and 0.81 g/t Au
- 732009: 31.7% Sb, 567 g/t Ag and 1.19 g/t Au
Location of five rock samples collected in October and November 2025, along with two rock samples collected in September 2025.
The samples averaged 39.2% Sb and 430 g/t Ag and were significantly larger than typical rock chips, averaging 3.6 kilograms per sample. They returned silver and gold values consistent with earlier sampling and historical production records.
These latest assays support and extend rock chip and soil sampling disclosed in September 2025, which the company said outlined a broad antimony-gold-silver mineralised footprint at Antimony Ridge.
“These results represent a significant validation of the Antimony Ridge Target and further demonstrate the exceptional grade potential of the Horse Heaven Project. Antimony grades of this magnitude are rarely reported globally, particularly exposed at surface, and the consistent association with strong silver and gold values materially enhances the projects overall value proposition," Craig Lindsay, Resolution's CEO of US Operations, said.
"Importantly, Antimony Ridge is emerging as a large, coherent, high-grade system within a strategically critical jurisdiction at a time when sure US antimony supply has become a national priority. With metallurgical test work underway and permitting progressing toward drilling and bulk sampling, we believe Horse Heaven is rapidly advancing toward becoming a highly strategic U.S critical minerals asset.”
Bulk sample and metallurgical test work
Resolution has collected about 100 kilograms of representative stibnite-silica vein material from the historic mine area for preliminary metallurgical test work and mineralisation characterisation.
Samples have been submitted to Kingston Process Metallurgy Inc. (Ontario, Canada) and Independent Metallurgical Operations Pty Ltd (Perth, WA), with results to be reported when available.
Golden Gate drilling update
Resolution also flagged pending assays from its 2025 drilling season at the Golden Gate target, with multi-element analysis underway for the final three diamond core holes and three reverse circulation holes.
The company said it would update the market once results are received.
Next steps
Near-term work at Antimony Ridge is focused on progressing permitting (via a submitted Plan of Operation) to enable drilling and bulk sampling. This will be followed by an initial drill program once approvals are in hand, alongside delivery of preliminary metallurgical results and planning for the next phase of Golden Gate drilling.