Perth, April 9, 2026 AEST — Red Mountain Mining Limited (ASX:RMX) has announced the planned recommencement of its United States field programs for antimony projects as winter conditions ease. The company frames these activities within the broader push to secure Western sources of critical minerals, engaging specialist contractors and appointing an experienced exploration adviser to accelerate work across Montana, Idaho and Utah. The announcement underscores an intent to move from reconnaissance to systematic surface programs that can rapidly generate drill targets and support resource definition.
The initial phase will begin with systematic mapping and sampling at the Thompson Falls Antimony Project, situated on the Montana–Idaho border and located less than 7 km from the only operating antimony smelter in the USA, US Antimony Corporation. Prior, limited rock-chip sampling from waste dumps at historical workings returned highly variable but locally very high grades, demonstrating priority target potential. Red Mountain plans to sequence work to follow a logical path: map, sample, model and then seek to test high-priority targets with drilling once permits and approvals are in place.
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Field programs and priority targets
The company intends to deploy geological teams for systematic surface work later this month. At Thompson Falls, the program will focus on locating the source of quartz-siderite-stibnite vein material observed in historical dumps and on mapping the distribution of mineralisation across the claim area. Early sampling returned values ranging from 820 ppm Sb up to an exceptional 36.5% Sb, with associated gold assays from 0.04 ppm to 1.12 ppm Au. The field crews will collect further oriented rock chips and channel samples to constrain the orientation and continuity of the mineralised veins and to prioritise targets for follow-up.
Thompson Falls sampling insights
Samples collected prior to winter from the historical Eastern Star Mine are notable: the average of those samples was approximately 8.7% Sb and 0.37 ppm Au, indicating both antimony and gold components to the system. Red Mountain will investigate other historical workings within the project to develop a broader geological framework. The objective is to translate surface geochemistry and structural mapping into a shortlist of drill-ready targets, so that the likely mineralised vein corridors can be tested for continuity and depth extent.
Idaho and Utah initiatives
After work at Thompson Falls, the exploration teams will move to Red Mountain’s central Idaho projects — Yellow Pine and Silver Dollar. Yellow Pine lies near active large-scale projects and shows the geological elements consistent with regional gold–antimony mineralisation, while Silver Dollar contains historical occurrences that previously returned up to 17.7% Sb in old mine records and significant precious metal values in nearby prospects. In Utah, reconnaissance mapping has identified pervasive silicification and argillic alteration; the company plans high-resolution drone magnetics to target structural corridors and then apply electrical methods such as controlled-source audio-frequency magnetotellurics (CSAMT) to define deep feeder zones.
Technical partnerships and industry expertise
To support the US program, Red Mountain has engaged Montana-based KC Harvey Environmental to provide field crews and regulatory navigation. KCH brings experience across Western US jurisdictions to help expedite approvals and field logistics. The company has also appointed Dr Max Baker to the advisory board; Dr Baker brings decades of global exploration leadership, including roles at major producers and junior developers. Together, these appointments aim to combine local on-the-ground capability with senior technical oversight to accelerate the pathway from mapping to drill testing.
Strategic context, funding and Australian assets
Red Mountain is positioning itself amid growing governmental support for critical minerals. Both Australian and US authorities identify antimony as strategic, prompting initiatives to boost domestic supply. The Australian Government’s AU$1.2 billion Critical Minerals Strategic Reserve and recent US federal permitting incentives such as FAST-41 reflect a policy backdrop that can assist project timelines. Red Mountain is also engaging US consultants with experience in grant and government-backed loan programs to pursue non-dilutive or low-dilution funding alternatives. Meanwhile, the company’s Armidale project in New South Wales remains active, with rock and soil assays up to 39.3% Sb and 1.36% Sb respectively, and drill planning progressing.
By combining targeted surface work, geophysics and external technical expertise, Red Mountain aims to convert high-grade surface anomalies into drill targets in 2026. The company’s staged approach — mapping, sampling, geophysical definition and then drilling — is intended to rapidly test the most prospective corridors for antimony and associated gold mineralisation while taking advantage of evolving public sector support for critical metal supply chains.
