Red Mountain Mining Ltd (ASX:RMX) Advances US Critical Minerals Portfolio with High-Grade Antimony Hits and Major Project Momentum

24 February 2026

Price Sensitive Announcement $

Highlights:

• Exceptional high-grade antimony results from Thompson Falls Project in Montana – peak rock chips up to 36.5% Sb and 0.65g/t Au, just 4.2km from US Antimony Corp’s (NYSE:UAMY) only operating US antimony smelter.
• More assays pending end of February; comprehensive surface mapping and sampling program set to launch next month to fast-track resource potential.
• Utah Antimony Project shows strong extension potential from neighbour American Tungsten and Antimony (ASX:AT4)’s high-grade Antimony Canyon system (up to 33% Sb, conceptual target 96,000–234,000t Sb metal) – recent visible stibnite noted nearby and mapping confirms similar geology on RMX ground.
• Idaho projects (Yellow Pine and Silver Dollar) strategically positioned near Perpetua Resources’ (NASDAQ:PPTA) giant Stibnite Gold-Antimony Project (4.8Moz Au + 67,100t Sb in reserves, construction underway) – historical high-grade antimony (up to 17.7% Sb) and strong silver/gold upside.
• Strengthened US technical team with drill permitting expertise accelerating advancement across all US assets.
• Well-funded ($2.18M cash) and pursuing non-dilutive government funding opportunities amid surging US and Australian demand for domestic critical minerals supply.

Overview:

Red Mountain Mining continues to build serious momentum in the US critical minerals space, securing prime positions in Tier-1 antimony districts as Western governments scramble to secure supply chains away from China.

Thompson Falls – High-Grade Antimony Right Next to the US Smelter

The Thompson Falls Project sits just 4.2km from UAMY’s (Market Cap ~AU$1.5 billion) Thompson Falls smelter and Stibnite Hill mine. First-pass sampling nailed multiple high-grade hits at the Eastern Star historical mine, with samples resembling UAMY’s quartz-stibnite veins – but adding bonus gold. The project also lies at the eastern edge of Idaho’s prolific Coeur d’Alene silver district (historically ~18% of US silver output plus major Pb, Zn, Au, Cu, Sb). A major surface program kicks off in March, including high-res geophysics to vector in drill targets.

Initial sampling of material from Eastern Star returned multiple samples with high antimony and gold results, with peak results of 36.5% Sb and 0.65g/t Au¹ (Figure 2; Figure 3).

Utah Antimony Project – Riding the Extension Wave

Directly adjoining AT4’s (ASX: AT4; Market Cap $200 million) Antimony Canyon Project – one of the USA’s largest and highest-grade undeveloped antimony assets. Recent discoveries (Northern Extension up to 3.59% Sb) and visible stibnite on adjacent ground point to the epithermal system potentially extending into RMX tenure. Mapping shows widespread silicification, argillic alteration, iron oxides, and quartz veining – classic signatures of the targeted mineralising system.

Idaho Power Play – Proximity to Major Development

Yellow Pine sits <2km from PPTA’s (Market cap AU$5.3 billion) Stibnite Gold-Antimony project, sharing key geological controls (faults, host rocks, historical workings). Silver Dollar features a historical high-grade stibnite vein (up to 17.7% Sb) plus surrounding prospects with bonanza silver (85.7g/t) and gold (17.5g/t) hits.With antimony firmly on the US and Australian critical minerals lists – and major funding tailwinds like the US EXIM’s US$10B Project Vault loan and Australia’s A$1.2B Critical Minerals Strategic Reserve – Red Mountain is perfectly placed to capitalise on the domestic supply push.The Company remains well-funded, backed by strong investors, and focused on minimising dilution while advancing its high-potential US and Australian critical minerals portfolio.

Thompson Falls Antimony Project Exploration to commence next month

Following initial outstanding results from the first-pass program, an extensive exploration program is planned to commence in March at the Thompson Falls Antimony Project.

It is anticipated that the surface mapping and sampling programs will identify prospective areas for more intensive follow up work, which is planned to include the collection of high-resolution magnetic and electrical data to directly identify and target prospective host structures, alteration and sulfide mineralisation for drill-testing.

Red Mountain has recently strengthened its US technical team with dedicated drill-permitting expertise, driving the permitting process forward across all of the Company’s US Critical Minerals Projects.

Red Mountain well placed to leverage current critical metal opportunities

Both the Australian and US Governments have explicitly identified antimony as a critical strategic metal, with significant constraints on supply and uncertainty around supply chain security. These constraints, which have included China limiting supply of the metal to western countries, has led to the Australian Government setting aside A$1.2 billion to establish a Critical Minerals Strategic Reserve, targeting antimony and rare earth elements, which is set to be operational by the second half of 2026. In the US, on 4 February 2026 the Export-Import Bank of the United States (EXIM) approved a Direct Loan of up to US$10 billion for Project Vault, a $US12 billion initiative that aims to fundamentally strengthen America’s critical minerals sector and establish a domestic strategic reserve for critical minerals by shielding domestic manufacturers from supply shocks, and funding expansion of U.S. production and processing of critical raw materials. This and other positive signals from the US Government have driven strong interest in exploration and development projects for antimony, with US Antimony Corporation, Perpetua Resources and other players moving rapidly to increase the country’s domestic smelter and processing capacity and seeking to secure new ore supply to meet an anticipated surge in domestic US demand.

Red Mountain closed the quarter well-funded with $2.18 million in cash, with the Company’s position set to be further strengthened by an expected non-dilutive OJEP funding rebate, as well as an Australian Government refund of approximately $130,000. Red Mountain continues to explore non-dilutive funding opportunities including government grants and funding specific to accelerating the secure supply of Critical Minerals to the US and West, with the intention of minimising shareholder dilution, as the Company progresses through advancing its portfolio of assets.

Supported by a strong and experienced investor base across Australia and the United States, including the ongoing support of three shareholders who have featured in the Top 20 of Larvotto Resources (ASX: LRV), Red Mountain is well positioned to advance its US and Australian Critical Minerals portfolio with the warm tailwind of an unprecedented shortage of Western Antimony supply and growing US and Australian Government demand for critical strategic commodities.