Broken Hill Mines Hits 25.8m at 11.7% in First Ever Drill Below Key Shear Zone
Broken Hill Mines strikes thick, high-grade silver-lead-zinc discovery below Rasp Mine’s Globe-Vauxhall Shear
Broken Hill Mines (ASX: BHM) has reported a significant new discovery of bulk tonnage, high-grade Ag-Pb-Zn mineralisation in the Centenary Zone at its 100%-owned Rasp Mine, representing the first ever targeted drilling below the Globe-Vauxhall Shear into this under-explored orebody. The headline intercept returned 25.8m @ 11.7% ZnEq, 323g/t AgEq (39g/t Ag, 2.3% Pb, 7.9% Zn, 0.2% Cu, 0.1g/t Au) from 415.1m in hole WMDD6391, approximately 500% wider and 27% higher grade than the 2024 Inferred Mineral Resource Estimate modelled for this location. The discovery sits only ~250m from existing Western Mineralisation operations, offering immediate brownfields leverage.
This marks a potential step-change in deposit scale at a mature operation. The proximity to producing infrastructure positions the Centenary Zone as a near-term development target with materially lower capital intensity compared to standalone greenfield projects.
When big ASX news breaks, our subscribers know first
Inside the standout intercept — what the drill core revealed
Hole WMDD6391 intersected a 40m-wide mineralised zone, significantly exceeding previous modelling for the Centenary Zone. The intercept included a higher-grade sub-interval of 10.9m @ 17.3% ZnEq, 479g/t AgEq (58g/t Ag, 4.1% Pb, 11.5% Zn, 0.1% Cu, 0.1g/t Au) from 422m.
The width and grade profile represent a material upgrade to the current Inferred Mineral Resource Estimate for Centenary of 4.8Mt @ 9.2% ZnEq, 255g/t AgEq (39g/t Ag, 2.4% Pb, 6.0% Zn). Initial mineralogical investigations identified the presence of Hedenbergite and Tetrahedrite within the drill core, indicating that Centenary more closely resembles the historic Main Lode ore body than the adjacent Western Mineralisation. This geological affinity suggests potential for a larger-scale deposit than previously modelled.
| From (m) | Interval (m) | ZnEq % | AgEq (g/t) | Detail |
|---|---|---|---|---|
| 398.2 | 4.8 | 6.7 | 185.4 | 15g/t Ag, 1.5% Pb, 4.6% Zn, 0.1% Cu |
| 407.0 | 3.0 | 4.1 | 114.5 | 10g/t Ag, 0.6% Pb, 2.9% Zn, 0.2% Cu |
| 415.1 | 25.8 | 11.7 | 322.8 | 39g/t Ag, 2.3% Pb, 7.9% Zn, 0.2% Cu, 0.1g/t Au |
| 454.0 | 1.0 | 8.8 | 242.4 | 54g/t Ag, 2.6% Pb, 4.5% Zn, 0.1% Cu, 0.1g/t Au |
Note: ZnEq and AgEq are calculated using the following assumptions: ZnEq% = Zn% + (Ag g/t × 0.036) + (Pb% × 0.754) + (Cu% × 2.497) + (Au g/t × 3.033). AgEq g/t = Ag g/t + (Pb% × 27.030) + (Zn% × 35.815) + (Cu% × 89.844) + (Au g/t × 109.136). Metal price and recovery assumptions: Zn $2,650/t (88.4%), Pb $2,000/t (88.3%), Ag $35/oz (75.0%), Cu $9,000/t (65%), Au $3,400/oz (65%). All elements in the calculation have a reasonable potential to be recovered and sold. Gold has yet to be systematically assayed across the Rasp Mine drilling programme. Metal equivalents should not be treated as final recoverable grades.
Broken Hill Mines — Company Statement
This result represents a major new discovery at the Rasp Mine, driving a full reinterpretation of the Centenary Zone’s ore understanding. Initial analysis demonstrates a strong similarity to Main Lode mineralisation, a potential step-change in deposit scale.
Why the Centenary Zone matters — an under-drilled giant next door
The Centenary Zone was discovered in 1983, sitting structurally below the Globe-Vauxhall Shear, which distinguishes it from the shallower Main Lode and Western Mineralisation ore bodies. Despite four decades since discovery, Centenary remains one of the least-drilled parts of the Rasp system, with only 24 holes ever completed into the orebody. The majority of these were drilled in the 1980s from surface.
The reason for this sparse drilling is technical rather than geological. Historically, no company has successfully drilled through the Globe-Vauxhall Shear without material distortion of the drill bit trajectory, leading to inaccurate holes and frequent abandonment. This structural barrier has left Centenary substantially under-tested despite its scale.
Broken Hill Mines has overcome this challenge through an innovative drilling approach. The company first drilled a large-diameter hole through the Shear, which was then cased. Smaller “daughter” holes were then placed through the cased hole, allowing drilling into the Centenary Zone without trajectory disruption.
For investors, this technical breakthrough unlocks a high-leverage exploration opportunity. The Centenary Zone is a large, under-drilled orebody located within 200–300m of existing operations. Development of Centenary offers a brownfields pathway with materially lower capital intensity compared to standalone projects, as it sits within reach of existing declines, ventilation and haulage infrastructure.
Centenary Zone geometry and scale:
- Current Inferred Mineral Resource Estimate: 4.8Mt @ 9.2% ZnEq, 255g/t AgEq (39g/t Ag, 2.4% Pb, 6.0% Zn)
- Strike length: ~1,600m
- Vertical plunge: ~280m
- Mineralisation remains open at depth and along strike in multiple directions
- Located ~200–300m from current Western Mineralisation operations
The combination of deposit scale, proximity to infrastructure, and low drilling density creates a rare brownfields exploration scenario with multiple upside vectors.
The investment case — bulk tonnage feed for a future plant expansion
Broken Hill Mines has positioned the Centenary Zone as a potential source of high-grade, bulk tonnage feed for medium-term plant expansion, complementary to the existing 750,000tpa operations at the Rasp Mine. The discovery intercept drives a full reinterpretation of the Centenary Zone’s ore understanding, with the Main Lode geological affinity representing the key thesis driver.
The Main Lode at Rasp was mined intermittently for approximately 140 years and is considered one of the most significant Ag-Pb-Zn sulphide systems globally. If Centenary demonstrates similar geology and scale to the Main Lode, it would represent a material expansion of the mine’s long-term production profile. The brownfields development pathway offers a lower-risk, capital-efficient route to increasing throughput compared to building standalone infrastructure.
The next major ASX story will hit our subscribers first
What happens next — accelerated drilling toward a Q4 CY26 resource upgrade
The company has outlined the following near-term catalysts following the discovery:
- Accelerated drilling programme underway into the Centenary Zone to confirm the discovery and test strike and depth extensions.
- Expedited reinterpretation of historic drilling within the Centenary Zone, incorporating the new geological model.
- Definition of a new exploration target prior to the Mineral Resource Estimate upgrade.
- Updated Mineral Resource Estimate for the Rasp Mine targeted for release in Q4 CY26.
- Further assay results expected in the coming weeks from ongoing drilling.
Broken Hill Mines has delivered a significant discovery in a structurally complex, historically under-drilled orebody sitting adjacent to producing infrastructure. The company now enters an accelerated exploration phase with multiple near-term catalysts that could materially reshape the Rasp Mine’s resource inventory and production outlook.
Want the Next Mining Breakthrough in Your Inbox?
Join 20,000+ investors receiving FREE breaking ASX news within minutes of release, complete with in-depth analysis. Big News Blast delivers market-moving announcements the moment they drop—click the “Free Alerts” button to stay ahead on Mining sector developments before the broader market reacts.