West Cobar Metals has revealed a significant uplift in antimony grades at its Bulla Park deposit after reanalysing drill core with peroxide fusion digest, suggesting the deposit's contained metal and economic potential may be materially higher than previously reported.
- Antimony grades increased by up to 68% via peroxide fusion reanalysis
- Average 14% uplift across key mineralised intervals
- Historic acid digest assays under-reported antimony content
- Current inferred resource: 20Mt at 0.58% copper equivalent including 0.10% antimony
- Deposit remains open along strike and at depth with strong metallurgical recoveries
Significant Antimony Grade Revision at Bulla Park
West Cobar Metals (ASX:WC1) has confirmed that antimony grades at its Bulla Park copper-antimony-silver deposit have been substantially under-reported in historic assays. By reanalysing drill core samples using a peroxide fusion digest method instead of conventional acid digest, the company recorded an average 14% increase in antimony grades across key mineralised intervals, with some intervals showing uplift as high as 68%. This finding points to a potentially material increase in contained antimony metal in upcoming Mineral Resource Estimate (MRE) updates.
Managing Director Matt Szwedzicki described the results as a “significant step forward,” highlighting that any increase in contained antimony directly enhances the deposit’s economic case given the metal’s strategic importance and strong global demand.
Resource and Metallurgical Implications
The current inferred Mineral Resource at Bulla Park stands at 20 million tonnes grading 0.58% copper equivalent (CuEq), which includes 0.10% antimony and 4.7 grams per tonne silver, reported at a 0.21% copper cut-off. The deposit contains approximately 60,000 tonnes of copper, 20,000 tonnes of antimony, and 3 million ounces of silver in situ, though the antimony uplift is not yet reflected in these figures.
Metallurgical testwork supports the commercial recovery of all three metals, with recoveries of 94.6% for copper, 82.6% for antimony, and 84.1% for silver. The ability to produce a separate antimony sulphide product alongside a saleable copper-silver concentrate adds to the deposit’s appeal.
Exploration Upside Across District-Scale Tenure
The Bulla Park deposit remains open both along strike and at depth, reinforced by a strong mineralisation-related gravity anomaly that extends beyond the current resource footprint. West Cobar’s district-scale position in the Cobar Basin now covers about 1,090 square kilometres with roughly 120 kilometres of strike, following recent licence applications that expand exploration potential significantly.
This expanded footprint aligns with the company’s broader strategy to grow its presence in the Cobar region, as detailed in its recent broadened Cobar West footprint announcement, which highlighted new licence applications and multiple gravity anomalies coinciding with historical mineralisation.
Next Steps Focus on Resource Upgrade and Drilling
West Cobar plans targeted drilling to expand high-grade zones at Bulla Park and incorporate the revised antimony grades into the next MRE upgrade. The company is also advancing metallurgical optimisation to refine processing pathways and maximise recoveries.
While the precise scale and timing of the resource upgrade remain uncertain pending formal MRE work, the confirmation of under-reported antimony grades marks a clear positive development for the project’s valuation and future feasibility assessments.
Bottom Line?
The confirmed antimony grade uplift at Bulla Park sets the stage for a potentially more valuable resource, but investors should watch for the upcoming formal resource update and drilling results to gauge the full impact.
Questions in the middle?
- How will the updated antimony grades influence the economics of the Bulla Park project once formally incorporated into the Mineral Resource Estimate?
- What results will targeted drilling deliver in expanding high-grade zones along strike and at depth?
- To what extent can metallurgical optimisation improve recoveries and processing costs for the polymetallic deposit?