Nagambie Resources has discovered a high-grade antimony-gold lode east of its current resource, averaging 40.5 g/t gold equivalent, prompting plans for extensive follow-up drilling to expand its JORC resource.
- Discovery of 7.0% antimony and 1.8 g/t gold over 1.83m estimated horizontal thickness
- Hole NAD056 intersected 7.3m downhole at 40.5 g/t gold equivalent (AuEq)
- C4 lode located 130m east of existing C1 lode, 123m below surface
- Plans underway for 50m x 50m drill pattern to delineate resource expansion
- Geological and metallurgical similarities to nearby Costerfield Mine support economic viability
Discovery Highlights
On 5 May 2025, Nagambie Resources Limited (ASX:NAG) announced a significant breakthrough at its Nagambie Mine in Victoria, revealing a high-grade antimony-gold (Sb-Au) lode, designated the C4 lode. The discovery hole NAD056 intersected a 7.3-metre downhole mineralised zone with an estimated horizontal thickness of 1.83 metres, grading an impressive 40.5 g/t gold equivalent (AuEq). This includes 7.0% antimony and 1.8 g/t gold, marking one of the company’s highest-grade intersections to date.
Located approximately 130 metres east of the previously known C1 lode and 123 metres below surface, the C4 lode discovery extends the known mineralised system significantly. The intersection’s grade and thickness suggest a potentially valuable addition to Nagambie’s existing JORC Inferred Resource, which currently stands at 539,000 tonnes at 3.9% Sb and 3.3 g/t Au, equating to 322,000 ounces AuEq.
Geological Context and Structural Model
The C4 lode fits neatly into Nagambie’s structural model, which identifies a semi-regular spacing of north-south striking antimony-gold veins, dipping steeply westwards. The spacing between the C lodes ranges from 100 to 150 metres, with the C4 lode’s 130-metre distance from C1 reinforcing this pattern. Nagambie’s Chairman, Kevin Perrin, highlighted the potential scale of the system, noting that with 3,500 metres of strike remaining untested, the discovery raises compelling questions about the ultimate size of the Nagambie Mine’s antimony-gold system.
Geologically, the mineralisation is hosted within narrow quartz and sulphide veins dominated by stibnite (Sb2S3), similar to the nearby Costerfield Mine, Australia’s only current producer of both gold and antimony. This similarity extends to the host rocks, fine-grained mudstones and siltstones, and the mineralogical characteristics, which bode well for metallurgical processing.
Economic Implications and Metallurgical Considerations
Market conditions further enhance the significance of this discovery. Both antimony and gold prices are near record highs, with antimony trading at approximately A$88,409 per tonne and gold at A$4,998 per ounce as of March 2025. These prices underpin the calculation of the gold equivalent factor (AuEq factor) at 5.50, which converts antimony grades into gold equivalent terms, reflecting their relative economic value.
Metallurgical recoveries are conservatively estimated at 93% for both antimony and gold, based on successful processing at the Costerfield Mine. Nagambie plans to apply similar treatment processes, confident that future testwork on representative drill core will replicate these recoveries. This supports the economic viability of mining and processing the newly discovered high-grade C4 lode.
Next Steps and Resource Expansion Plans
Following this discovery, Nagambie intends to undertake systematic drilling on a 50m by 50m grid to delineate the C4 lode’s extent and continuity. This program aims to convert the new mineralisation into an updated JORC Mineral Resource Estimate, potentially boosting the overall resource base significantly.
The company also plans to explore additional C lodes within a 1,500-metre radius east of C4 and up to 2,000 metres west/south-west of C3, leveraging the structural model to guide exploration. These efforts could unlock further high-grade antimony-gold mineralisation, enhancing Nagambie’s position in a strategically important commodity sector.
Technical Rigor and Reporting Standards
The announcement is supported by rigorous sampling, assaying, and geological logging protocols consistent with the JORC Code (2012 Edition). Diamond drilling was conducted with HQ diameter core, with samples carefully selected and assayed using industry-standard fire assay and ICP methods. Bulk density measurements and assay weighting were applied to estimate practical mining widths and grades.
Independent verification by Adam Jones Geological Services ensures the reliability of the reported results. The company maintains transparent reporting and plans to update the market as further drilling and metallurgical testwork progress.
Bottom Line?
Nagambie’s high-grade antimony-gold discovery could redefine its resource scale, but follow-up drilling and metallurgical validation remain critical.
Questions in the middle?
- How extensive is the C4 lode beyond the initial 7.3m intersection?
- Will metallurgical testwork confirm the assumed 93% recovery rates for antimony and gold?
- How will sustained commodity price fluctuations impact the economic feasibility of mining this high-antimony ore?