Boab Metals Grows Sorby Hills Resource 7% to 50.6Mt as Construction Advances
Key Takeaways
- Boab Metals' updated MRE for Sorby Hills has grown 7% to 50.6Mt at 3.0% Pb, 34 g/t Ag and 0.4% Zn, with contained silver increasing by 1.6Moz.
- Measured and Indicated Resources across the three key mine-plan deposits — Bimota, Omega and Norton — increased by 10%, directly strengthening confidence in the early years of planned production.
- The resource growth was driven by 305 new assays at Norton, a new NSR domaining methodology that unlocked previously excluded silver-rich mineralisation, and the removal of a 1% tonnage reduction factor across the three core deposits.
- Phase IX drilling results, including a 12.6m intercept at 121 g/t Ag and 7.65% Pb at Omega, have not yet been incorporated into this MRE, representing identifiable upside to future estimates.
- Boab now holds 100% of Sorby Hills following its acquisition of Yuguang's 25% stake in January 2026, with the project fully funded, under construction, and targeting first production in H2 2027.
Sorby Hills resource grows to 50.6Mt as Boab advances towards first production
Boab Metals has released an updated Mineral Resource Estimate (MRE) for its 100%-owned Sorby Hills Silver-Lead Project, delivering a 7% increase in resource tonnage to 50.6Mt at 3.0% Pb, 34 g/t Ag and 0.4% Zn. The update represents a meaningful de-risking step for a project that is already fully funded, under construction, and targeting first production in H2 2027.
The three deposits that form the backbone of the Sorby Hills mine plan, Bimota, Omega and Norton, were the focus of this update. Infill drilling completed since the previous MRE (December 2021) has increased Measured and Indicated Resources across these deposits by 10%, providing greater confidence in the planned production schedule. A Net Smelter Return (NSR) domaining approach also enabled the inclusion of previously excluded mineralisation, contributing to a 1.6Moz increase in contained silver.
Simon Noon, Managing Director and CEO
“The updated Mineral Resource Estimate represents another important milestone for Sorby Hills, delivering growth in resource tonnage and contained silver while further strengthening confidence in the Mineral Resources underpinning our mine plan. Importantly, the increase in Measured and Indicated Resources across key deposits provides greater confidence in the early years of planned production as we advance Sorby Hills towards development. These results demonstrate the value of our targeted drilling programs and refined resource modelling, reinforcing the quality and scale of the Sorby Hills Resource.”
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What changed and why it matters
The 2026 MRE update was undertaken by ERM International Group (ERM) and proceeded in three distinct stages. Understanding each stage helps explain where the tonnage and silver growth actually came from.
Three deposits updated, three key drivers
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Norton Deposit: An additional 305 assays from diamond and reverse circulation (RC) drilling completed since the 2021 MRE were incorporated, alongside a refreshed geological interpretation of the deposit.
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NSR domaining approach: A Net Smelter Return methodology was adopted to identify additional mineralisation domains across Bimota, Omega and Norton. This approach converts lead and silver assay results to a silver equivalent grade, using a 40 g/t AgEq cut-off to guide geological interpretation. It unlocked low-grade lead mineralisation (typically less than 1% Pb) associated with higher-grade silver mineralisation (greater than 10 g/t Ag) that was previously excluded under the lead-only domaining approach. A total of 23 new NSR domains were modelled: five at Bimota, twelve at Omega and six at Norton.
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Removal of 1% tonnage reduction factor: A porosity reduction factor previously applied at the reporting stage for Bimota, Omega and Norton has been removed. The additional data now available, together with updated modelling and review by the Competent Person, was considered sufficient to support its removal. This factor continues to apply to Aprilia, Alpha and Beta.
Importantly, the Aprilia, Alpha (Pb), Alpha (Zn) and Beta deposits were not re-estimated as part of this update and remain unchanged from the prior MRE.
Resource summary
| Deposit | Classification | Tonnes (Mt) | Pb % | Ag g/t |
|---|---|---|---|---|
| Bimota | Measured | 1.4 | 3.8 | 19 |
| Bimota | Indicated | 1.6 | 3.1 | 19 |
| Bimota | Inferred | 0.2 | 2.3 | 12 |
| Bimota Sub-total | 3.2 | 3.4 | 19 | |
| Omega | Measured | 8.6 | 3.3 | 37 |
| Omega | Indicated | 6.7 | 3.3 | 31 |
| Omega | Inferred | 3.1 | 2.6 | 26 |
| Omega Sub-total | 18.4 | 3.2 | 33 | |
| Norton | Measured | 3.1 | 3.7 | 67 |
| Norton | Indicated | 2.7 | 2.8 | 32 |
| Norton | Inferred | 17.1 | 2.3 | 27 |
| Norton Sub-total | 22.8 | 2.5 | 33 | |
| Grand Total | 50.6 | 3.0 | 34 |
Source: Table 1, Boab Metals ASX Announcement, 29 September 2026. Grand Total includes Aprilia, Alpha and Beta deposits. Figures rounded.
Why confidence categories matter for investors
Not all resource tonnes are equal. The JORC Code, which governs how Australian mining companies report mineral resources, classifies estimates into three categories based on the level of geological confidence behind them.
- Measured is the highest confidence category. It is supported by detailed drilling at close spacing and underpins production scheduling.
- Indicated provides sufficient confidence for economic assessment, including feasibility studies, but carries more uncertainty than Measured.
- Inferred is the lowest confidence category. Inferred Resources cannot underpin a mine plan and carry the highest estimation risk.
The 10% increase in Measured and Indicated Resources across Bimota, Omega and Norton matters precisely because these are the deposits that feed the early years of planned production at Sorby Hills. More high-confidence tonnes mean the production schedule is standing on firmer ground.
One nuance worth understanding is what the NSR domaining approach actually represents. It does not create new ore. It accounts for mineralisation that was already visible in drill holes but had previously been excluded because the lead grade alone fell below the cut-off threshold. By incorporating silver values alongside lead, the NSR methodology captures this mineralisation properly for the first time.
Separately, recent Phase IX drilling results, including 12.6m at 121 g/t Ag and 7.65% Pb from 23m at the Omega deposit, have not yet been incorporated into this MRE. These are assay results sitting outside the current estimate, representing potential future upside as additional drilling programs are planned to upgrade Inferred to Indicated resources.
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The investment case: a fully funded project with a growing resource base
For investors following Boab Metals, this MRE update is best read as continued de-risking of a construction-stage project, not a standalone exploration event. Several components of the investment case are worth holding together.
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Project economics context: The 2023 Feasibility Study (FS) demonstrated pre-tax economics including a NPV of A$370M, an IRR of 35%, and average annualised EBITDA of A$119M. These figures are from the 2023 FS and have not been revised or updated by this MRE announcement. They are presented here as existing context only.
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100% ownership: Boab completed its acquisition of Yuguang’s 25% stake in the Sorby Hills Project in January 2026, meaning the full economic benefit of the project now accrues entirely to BML shareholders.
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Resource upside: Phase IX drilling results have not yet been incorporated into the MRE, and further drilling programs are planned to upgrade Inferred Resources to the Indicated category.
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Construction underway: The project is fully funded and under construction, targeting first production in H2 2027.
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Silver market positioning: Boab is advancing towards becoming a significant new silver and lead producer, with the updated resource base reinforcing the scale of the Sorby Hills deposit.
The trajectory here is consistent: each successive MRE update has added tonnage and silver ounces, drilling confidence has increased in the deposits that matter most to the early mine plan, and the project itself is moving through construction rather than sitting in the feasibility phase. The resource estimate released on 29 September 2026 continues that pattern.
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