• Of 195 rock chip samples, 37 assayed above 0.1 per cent copper, with a peak of 19.15 per cent at Mammoth.
  • Tungsten skarn mineralisation was confirmed at all four prospects, with maximum tungsten trioxide assays of up to 0.55 per cent.
  • The samples are reconnaissance only, no drilling has been reported, and drilling is expected to start in the 2027 Northern Hemisphere field season.

Red Mountain Mining Ltd (ASX:RMX) has released a desktop study highlighting copper potential at its 100 per cent owned Pioneer Tungsten Project in south-west Montana, USA. Rock chip samples from three prospects returned copper grades of up to 19.15 per cent, alongside tungsten skarn mineralisation confirmed at all four prospects. The company says it is also reviewing new copper Assets to complement its antimony and tungsten projects.

The copper results

Of 195 rock chip samples, 37 (19 per cent) assayed above 0.1 per cent copper, and some of these exceed 1 per cent. The other 158 samples were below 0.1 per cent. The highest values by prospect were 19.15 per cent copper at Mammoth, from a skarn outcrop, 6.72 per cent at Greenstone and 3.92 per cent at Glow Worm. At Mammoth, only two of 10 reconnaissance samples were above 0.1 per cent copper. Full sample details were published in the company's announcements of 14 September 2026 and 1 July 2026.

The high-grade copper samples are concentrated at Glow Worm, the northern part of Greenstone and Mammoth, all of which had small-scale artisanal copper, silver and gold production in the early twentieth century. Historical records cited by the company include 96 tonnes of Greenstone ore yielding 3.0 tonnes of copper, and 79 tonnes of ore from the Ivanhoe Mine claims in 1928 and 1929 yielding 5.7 tonnes of copper. Glow Worm had six adits and four shallow shafts from 1919 but no recorded production.

Tungsten and project setting

Pioneer covers 517 hectares across four prospects in three claim blocks on US Bureau of Land Management land, on the eastern Margin of the Mount Torrey Batholith. Maximum tungsten trioxide assays were 0.55 per cent at Greenstone, 0.40 per cent at Glow Worm, 0.32 per cent at Lost Creek and 0.29 per cent at Mammoth. Magnetic modelling by Arrow Geosciences indicates subsurface magnetic bodies that the company interprets as the granodiorite source of the skarn, and which may host limestone-hosted tungsten skarn at shallow depth beneath quartzite.

The announcement also notes that Almonty Industries bought adjacent claims in November 2025, and that the Gentung deposit has a resource of 6.83 million tonnes at 0.315 per cent tungsten trioxide. This is regional background and not a Red Mountain resource. The company also describes south-west Montana as a significant copper province and cites the Butte deposits, about 60 kilometres north-east, as context. These comparisons do not indicate that Pioneer holds similar mineralisation.

Next steps

The company's United States field team is finalising plans for upcoming surface mapping and sampling for tungsten and copper, expanding into previously unexplored areas. Drill targets are to be prioritised after that work, with drilling expected to start in the 2027 Northern Hemisphere field season. Drill testing of the downdip extension of surface mineralisation at one or more locations is subject to positive assay results.

Red Mountain's other projects include the Armidale Antimony-Gold Project in New South Wales, where rock chips have returned up to 39.3 per cent antimony, and the Utah and Thompson Falls antimony projects. The Competent Person for the Pioneer results is contract geologist Mark Mitchell.