Red Mountain Mining reports exceptional antimony sampling results at Idaho-Montana border

The junior entered the American mining sector in September

Rowan Dunne

Published

3 hours ago

Red Mountain Mining Ltd (FRA: RM0) (ASX: RMX) has revealed encouraging results from recent sampling at its Thompson Falls project on the Montana-Idaho border.

Teams collected rock samples from historic underground workings and a surface pit, producing average antimony grades of 8.7 per cent and gold at 0.37 grams per tonne. Individual samples peaked at 36.5 per cent antimony and 1.12 grams per tonne gold, with one spot check on a stibnite-rich piece reaching 47.3 per cent antimony (Sb).

These outcomes point to notable mineralization as the company advances mapping and further evaluation. The site lies just 4.2 kilometres from the country’s only operating antimony processing plant, also named Thompson Falls, managed by United States Antimony Corp (NYSEAMERICAN: UAMY).

Grades represent significant improvement

The Thompson Falls samples show clear improvement over earlier work at Red Mountain’s other U.S. projects.

Initial sampling in Utah and Idaho often returned antimony in the 1 to 5 percent range, with more variable gold values and less consistency. In contrast, these new figures deliver higher averages and standout peaks, strengthening the overall profile of the company’s American assets.

When compared to recent high-grade sampling reports from other operators in the U.S., Red Mountain’s results hold up reasonably well.

For instance, Resolution Minerals Ltd (OTCMKTS: RLMLF) (FRA: NC3) (ASX: RML) reported surface stibnite samples averaging 39.2 per cent Sb (with peaks up to 48.7 per cent) from its Horse Heaven project in Idaho in early 2026. Another ASX-listed operator, Trigg Minerals Ltd (ASX: TMG) (OTCMKTS: TMGLF) (FRA: ATA), announced rock chip and channel samples reaching up to 29.4 per cent antimony at Utah’s Antimony Canyon project in late 2025.

Meanwhile, other explorers like Military Metals Corp (CNSX: MILI) (OTCMKTS: MILIF) (FRA: QN90), NevGold Corp (CVE: NAU) (OTCMKTS: NAUFF) (FRA: 5E50) and Locksley Resources Ltd (OTCMKTS: LKYRF) (ASX: LKY) (FRA: X5L) have highlighted anomalies and Sb samples in the 9.75 to 25 per cent range in Nevada and California.

Red Mountain’s averages and peaks place it among the stronger recent surface finds in these U.S. districts.

Establishing a strong American footprint

Red Mountain Mining entered the U.S. market in September of 2025 by staking claims in Utah focused on antimony near existing infrastructure.

It followed with the acquisition of the Silver Dollar property in Idaho, a historic producer of high-antimony ore during the 1940s wartime era. This expanded the company’s Idaho footprint by about 80 per cent, bringing in precious metals along with prospective uranium and mercury.

Red Mountain then added the neighbouring Yellow Pine site, residing only 2 kilometres from Perpetua Resources Corp (TSE: PPTA) (NASDAQ: PPTA).

These moves form part of a clear strategy to prioritize domestic assets amid national efforts to build reliable supplies of critical minerals. Red Mountain has assembled a U.S.-based technical team to push exploration forward.

That being said, the path ahead carries risks, such as volatile metal prices, permitting hurdles in environmentally sensitive areas and the inherent challenges of advancing early-stage projects in remote terrain.

$RMX

OUTSTANDING #ANTIMONY AND #GOLD RESULTS FROM THOMPSON FALLS ANTIMONY PROJECT

New assay results from the historical Eastern Star #Silver–#Lead mine within Red Mountain's Thompson Falls #Antimony Project on the Montana-Idaho border have returned consistently High-Grade… pic.twitter.com/YznUgqBW0K

— Maurice Salvador (@SalvadorMaurice) March 1, 2026