Broken Hill Mines (ASX: BHM) has unveiled a significant new high-grade silver, lead, and zinc discovery at its Centenary Zone, expanding the resource with thick, high-grade intercepts that connect a 1,600m strike length and promise a resource upgrade later this year.
- Major new discovery of high-grade silver, lead, zinc mineralisation
- Wide intercepts outside existing Mineral Resource Estimate
- Silver grades up to 4.4 times historical estimates
- Drilling connects northern and southern Centenary resource zones
- Resource upgrade targeted for Q4 2026
Major High-Grade Intercepts Expand Centenary Zone
Broken Hill Mines Limited (ASX:BHM) has confirmed a major new discovery of thick, high-grade silver, lead, and zinc mineralisation at its 100% owned Rasp Mine’s Centenary Zone. Recent drilling below the Globe-Vauxhall Shear has delivered wide intercepts that significantly exceed the existing Mineral Resource Estimate (MRE), including a standout 17.8 metres grading 10.1% zinc equivalent (ZnEq) and 280 grams per tonne silver equivalent (AgEq), with peak silver grades hitting 173g/t; roughly 4.4 times higher than historical Centenary estimates.
These results not only expand the known resource but crucially connect the northern and southern portions of the Centenary MRE across a 1,600-metre strike length, suggesting a continuous high-grade zone. This breakthrough could materially increase the scale and grade profile of the resource, with BHM planning an MRE upgrade in the fourth quarter of calendar 2026.
Innovative Drilling Unlocks Previously Inaccessible Zones
BHM’s success stems from pioneering targeted underground drilling beneath the challenging Globe-Vauxhall Shear; a geological fault that had previously foiled accurate drilling attempts. By first drilling a large diameter hole through the shear and casing it, the company was able to deploy smaller daughter holes to precisely target the Centenary Zone without distortion.
This approach yielded thick, high-grade intercepts, such as hole WMDD6400W1, which returned 17.8m at 10.1% ZnEq including a 5.4m section grading 19.5% ZnEq and 540g/t AgEq. Another hole, WMDD6391W1, delivered 25.8m at 11.7% ZnEq, substantially wider and higher grade than the 2024 inferred resource estimate, highlighting significant upside potential.
Geological Similarity to Main Lode Suggests Step Change
Mineralogical analysis reveals that the Centenary mineralisation closely resembles the geology of the Main Lode ore body, historically the highest-grade zone at Rasp. This similarity hints at a potential step change in both grade and scale for the Centenary Zone, which until now has been sparsely drilled with only 24 holes, mostly from surface and dating back decades.
The Centenary Zone extends over a 1,600m strike length and plunges vertically for approximately 280m, remaining open at depth and along strike. Its proximity; just 250 metres; to existing Western Mineralisation operations offers a brownfields development opportunity with lower capital intensity, potentially underpinning a plant expansion for BHM’s 750,000 tonnes per annum processing capacity.
Further Drilling and Assays Underway Ahead of Resource Upgrade
Drilling continues with the latest hole, WMDD6389A, visually intersecting up to 35 metres of mineralisation pending assay results. These forthcoming assays will be critical to refining the Exploration Target and underpinning the MRE upgrade scheduled for late 2026.
The company is also reinterpreting historic drilling data to better understand the Centenary Zone’s structural complexity and mineralisation geometry, which has been challenging due to folding and shearing episodes. This reinterpretation aims to robustly define the resource and support future mine planning.
Pinnacles Mine Operations Continue to Complement Growth
Alongside Rasp, BHM operates the Pinnacles Mine under a joint venture, with ore trucked 15km to the Rasp processing plant. The Pinnacles Mine contributes a high-grade silver-rich feed, with profits shared approximately 70% to BHM. This multi-source ore feed strategy supports operational flexibility and production growth, complementing Rasp’s expanding resource base.
Bottom Line?
The Centenary Zone discovery could redefine Rasp Mine’s production profile, but pending assays and complex geology mean investors should watch closely for the upcoming resource upgrade.
Questions in the middle?
- How will the pending assays from WMDD6389A influence the scale and grade of the Centenary resource?
- What are the capital and operational implications of developing the Centenary Zone as a brownfields expansion?
- How might the reinterpretation of historic drilling data affect confidence levels in the resource classification?