Broken Hill Mines (ASX: BHM) has confirmed a major new discovery of thick, high-grade silver, lead, and zinc mineralisation at its Centenary Zone, extending the resource strike length to 1,600m and significantly exceeding historical estimates.
- Major new high-grade discovery at Centenary Zone
- Wide intercepts up to 35m thick with assays pending
- Silver grades up to 4.4 times historic resource estimates
- Drilling connects northern and southern resource zones over 1,600m
- Resource upgrade targeted for Q4 2026
Major New Discovery at Centenary Zone
Broken Hill Mines Ltd (ASX:BHM) has unveiled a significant upgrade to its Centenary Zone at the Rasp Mine, confirming a major new discovery of thick, high-grade silver, lead, and zinc mineralisation. Recent underground drilling below the Globe-Vauxhall Shear has delivered wide intercepts that materially exceed the historical Mineral Resource Estimate (MRE), including standout assays of up to 173g/t silver and 19.5% ZnEq over 5.4 metres.
The highlight drill hole WMDD6400W1 returned 17.8m at 10.1% ZnEq and 280g/t AgEq from 420m, including a 5.4m section grading 19.5% ZnEq and 540g/t AgEq. This intercept notably connects the northern and southern portions of the Centenary resource across a strike length of approximately 1,600 metres, effectively expanding the known mineralisation footprint.
Resource Expansion and Geological Significance
The silver grades reported are up to 4.4 times higher than those in the existing Centenary MRE, underscoring the potential for a step-change in the resource’s scale and value. Mineralogical analysis suggests the Centenary mineralisation shares a close affinity with the Main Lode ore body rather than the adjacent Western Mineralisation, hinting at a richer and more extensive deposit than previously understood.
Additional drilling, including the recently completed hole WMDD6389A, has visually confirmed a mineralised zone up to 35 metres thick, with assays pending. This thick zone sits strategically close, about 250 metres, to existing mining infrastructure, offering a brownfields development pathway that could support the current 750,000 tonnes per annum processing capacity and potentially justify plant expansion.
Innovative Drilling Techniques Unlocking New Zones
Targeted underground drilling beneath the Globe-Vauxhall Shear has been enabled by an innovative approach involving large diameter cased holes through the shear, allowing precise daughter holes to be drilled into the Centenary Zone without trajectory distortion. This technique marks the first successful targeted drilling below the shear, overcoming historical challenges that limited prior exploration to just 24 mostly surface holes.
The new drilling campaign has already yielded intercepts significantly thicker and higher grade than historical data, supporting a full reinterpretation of the Centenary Zone’s geology and mineralisation. The company is now fast-tracking reinterpretation of historic drilling data alongside ongoing exploration to delineate an Exploration Target ahead of a planned MRE update in Q4 2026.
Strategic Implications for Rasp Mine Operations
Centenary’s proximity to current operations at the Rasp Mine means it could provide a substantial new feed source for the processing plant, enhancing operational flexibility and potentially extending mine life. The discovery’s scale and grade also raise the prospect of medium-term plant expansion, supporting Broken Hill Mines’ growth ambitions.
Alongside the Centenary Zone, BHM continues to operate the Pinnacles Mine under a joint venture, with ore processed at Rasp. The integrated strategy of multiple ore sources and ongoing exploration underpins a robust pipeline of development opportunities.
Bottom Line?
BHM’s Centenary Zone discovery reshapes the Rasp Mine’s resource profile, but pending assays and complex geology mean the full commercial impact remains to be seen.
Questions in the middle?
- How will pending assay results from WMDD6389A influence the upcoming resource upgrade?
- What operational changes might be needed to integrate Centenary’s bulk tonnage feed into existing processing?
- Could the geological similarity to the Main Lode translate into higher-grade zones beyond current drilling?