Red Mountain Mining (ASX:RMX) Silver Dollar Mine Shows Strong Silver Prospectivity

11 December 2025

Price Sensitive Announcement $

Highlights:

• A technical study on the Silver Dollar Project in Idaho has highlighted the Silver and Gold
  potential of the locality with prospects identified immediately surrounding Red Mountain’s claims reporting historical assays of up to 85.7 g/t Silver and 17.5 g/t Gold*
• Red Mountain’s Silver Dollar Project features multiple Antimony, Silver and Gold mineral occurrences, including the previously mined “Silver Dollar Mine”, a 10m deep shaft targeting a massive stibnite vein up to 1m thick
• Previous production from the Silver Dollar Mine has estimated average ore grades of 17.7% Antimony, including grade of 14.6% Antimony and 6.9 g/t Silver from a single sample (ASX: 7 October 2025)
• RMX is set to commence its maiden exploration program at the Silver Dollar Project this week
• Red Mountain commissioned the study after acquiring the project in October, to identify high priority targets at the historic Silver Dollar Antimony mine:
  o Additional new claims for expansion include the strong Silver & Gold prospects
  o RMX intends to acquire the claims at the commencement of exploration program
• The stibnite vein mineralisation at the Silver Dollar Project is related to an ENE-striking, steeply N-dipping fault and the host rocks display an analogous geological setting to Perpetua Resources’ (Nasdaq: PPTA) Stibnite Gold-Antimony Project (4.8Moz Au and 148 Mlbs Sb)
• Silver was recently added to the US Critical Minerals list and complements RMX’s portfolio
• Silver prices have also surged higher, breaking new record highs above USD$60 per ounce
• Antimony price strength has been sustained, trading at USD$44,000 per tonne, coupled with the news of China’s Antimony oxide export volumes falling sharply month-on-month in October (Source: metal.com 21/11/2025)
• The Company continues to assess projects in the Critical Minerals sector, with the mission of seeking to meet the urgent and unprecedented demand in the United States and the West for reliable and fast-tracked sources of Critical and Strategic Metals

Overview:

Red Mountain Mining Limited has announce the results of a technical study at the Silver Dollar Antimony Project and adjacent area. The study highlights the Silver and Gold potential of the locality with prospects identified immediately surrounding Red Mountain’s claims reporting strong historical assays of up to 85.7 g/t Silver and 17.5 g/t Gold. RMX’s technical team intends to expand the Silver Dollar Project to include these highly prospective areas as the launch of the first-pass sampling program commences this week. The project is located southeast of both RMX’s recently expanded Yellow Pine Antimony Project1, and Perpetua Resources’ (Nasdaq: PPTA / TSX: PPTA; Market Cap AU$6.67 billion) Stibnite Gold-Antimony Project, which is the largest known antimony deposit in the USA, with a Proven and Probable Reserve of 104 Mt @ 1.33g/t Au and 0.06% Sb for 4.8Moz Au and 148Mlbs Sb2.

RMX’s Silver Dollar claims encompass four known alluvial gold-silver placers, the Kelly & Joe gold-silver prospect and two reported vein antimony mineral occurrences, including the Silver Dollar Mine (Figure 1), which features a 10m deep shaft sunk into fractured granodiorite in 1944, targeting a massive stibnite vein up to 1m thick.

Gold and Silver – Precious metals Potential at Silver Dollar

As shown on Figure 1, the area including and surrounding Red Mountain’s Silver Dollar claims features multiple bedrock and alluvial silver and gold mineral occurrences, many of which feature historical pits and adits. The bedrock occurrences, which are named on Figure 1 and summarised in Table 1, are structurally controlled and associated with quartz veining and shear zones within the Idaho Batholith. Due to their narrow width, these dykes are not shown in the published USGS mapping shown in Figure 1, but are clearly locally important in focusing hydrothermal fluid flow and as hosts for vein-style precious metal mineralisation.

Assay data for the bedrock precious metal occurrences shown in Figure 1 and listed in Table 1 are indicative of potential for high tenor mineralisation, with quartz vein samples returning best results of 6.9 g/t Au from Blind Ledge and 85.7 g/t Ag from Klondyke; and a selection of samples from Iron Crown with observed visible gold found to contain 17.5 g/t Au and 14.7 g/t Ag (Table 1)

Full ASX Announcement: https://hotcopper.com.au/threads/ann-silver-dollar-mine-area-reveals-strong-silver-prospectivity.8933941/