Polymetals Hits 687 AgEq g/t at Endeavor as Ore Reserve Estimate Nears
Key Takeaways
- Final drilling at the Upper Main Lode returned a headline intercept of 14.2m @ 687 AgEq g/t from hole POL038, including 494 g/t Ag, 4.8% Zn, 7.1% Pb and 0.75 g/t Au.
- A supergene chalcocite layer within POL038 assayed 0.7m @ 9.2% Cu and 1,195 g/t Ag from 62.6m depth — a bonus copper-silver discovery within the oxidised zone.
- The oxidised zone was deliberately excluded from the formal Mineral Resource, meaning any high-grade material recovered during development represents incremental upside not yet captured in the resource estimate.
- The Upper Main Lode sulphide resource of 1.6 Mt @ 8.5% Zn, 6.0% Pb and 235 g/t Ag sits materially above Endeavor's global resource average of 7.5% Zn, 4.2% Pb and 82 g/t Ag across all JORC categories.
- An Ore Reserve estimate covering all Endeavor orebodies is expected in Q2 FY27, converting the expanded 20.7 Mt resource into a formal mine plan with quantified production and economics.
Upper Main Lode drilling wraps up with high-grade oxidised intercepts
Polymetals Resources Ltd has completed its Upper Main Lode drilling program at the Endeavor Mine near Cobar, New South Wales, with final assay results now in hand. This program is the one that progressed from testing a new geological interpretation all the way through to defining the recently announced Mineral Resource of 1.6 Mt @ 8.5% Zn, 6.0% Pb and 235 g/t Ag.
These final holes were not drilled into the sulphide resource itself. They targeted the shallower oxidised and supergene zone sitting above it, a geologically distinct and more variable domain that was deliberately excluded from the formal resource estimate.
The standout result comes from drill hole POL038, which returned 14.2 m @ 687 AgEq g/t (494 g/t Ag, 4.8% Zn, 7.1% Pb and 0.75 g/t Au). Within that same hole, a supergene chalcocite layer at the base of the oxidised zone assayed 0.7 m @ 9.2% Cu and 1,195 g/t Ag from 62.6 m depth — a notable bonus discovery within what is already a high-grade system.
The top intercepts from this final phase of drilling are:
- POL038: 14.2 m @ 687 AgEq g/t (494 g/t Ag, 4.8% Zn, 7.1% Pb, 0.75 g/t Au)
- POL031: 36.2 m @ 130 AgEq g/t (101 g/t Ag, 3.2% Pb, 0.69 g/t Au)
- POL036: 13.4 m @ 93 AgEq g/t (18 g/t Ag, 8.3% Pb)
Note: AgEq figures do not include gold in the calculation, per the company’s stated methodology.
Mine design and Ore Reserve estimation are now progressing, with the program considered complete.
Jess Oram, Executive Director
“The final results complete a highly successful Upper Main Lode drilling program which progressed from testing a new geological interpretation to defining a significant new Mineral Resource. These latest holes tested the difficult oxidised and supergene zone above that resource, where weathering has substantially modified the original sulphide mineralisation and resulted in much greater grade variability and locally poor core recovery. Importantly, potential development required to access the high-grade Upper Main Lode Resource will provide direct exposure of this zone, allowing its mineralisation to be progressively mapped and sampled as mining advances.”
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Oxidised zones explained: why grade variability isn’t the whole story
Weathering transforms a sulphide ore body from the top down. As surface water and oxygen penetrate over geological time, they chemically alter the original sulphide minerals and redistribute metals throughout the upper portion of the system. In zinc-lead-silver deposits like Endeavor, zinc tends to be more soluble and leaches away, while lead, silver, and sometimes gold concentrate locally in irregular pockets. That is exactly what the POL031 and POL036 results show: broad lead intervals with highly variable silver and generally negligible zinc.
The result is a zone that is geologically complex and difficult to characterise with drilling alone. Core loss of 1.5% to 70% across several reported intervals in this program means grades reflect only the material that was recovered. The company has noted that development mapping, face sampling, and grade control are better suited to defining the distribution of mineralisation within this zone.
Importantly, this oxidised zone was deliberately excluded from the formal Mineral Resource estimate. That exclusion does not diminish the resource; it simply reflects appropriate geological conservatism. Any high-grade material encountered during development will be assessed as potential direct shipping ore — material that may be extracted and sold without processing — representing incremental upside embedded in the existing mining plan rather than a separate cost.
Where the Upper Main Lode sits within Endeavor’s bigger picture
The Upper Main Lode resource forms part of Endeavor’s updated global in-situ Mineral Resource, announced on 7 September 2026, totalling 20.7 Mt @ 7.5% Zn, 4.2% Pb and 82 g/t Ag at a 5% Pb+Zn cut-off. The table below shows how that resource breaks down by JORC classification:
The earlier Endeavor Mine Upper Main Lode resource update confirmed drilling consistency across the sulphide zone and advanced the geological interpretation that ultimately underpins the 1.6 Mt @ 8.5% Zn, 6.0% Pb and 235 g/t Ag Mineral Resource announced ahead of this final oxidised-zone phase.
| JORC Category | Tonnes (Mt) | Zinc (%) | Lead (%) | Silver (g/t) |
|---|---|---|---|---|
| Measured | 5.9 | 7.6% | 4.6% | 82 |
| Indicated | 11.1 | 7.5% | 4.3% | 86 |
| Inferred | 3.7 | 7.4% | 3.1% | 70 |
| Total | 20.7 | 7.5% | 4.2% | 82 |
The Upper Main Lode’s grade profile — 8.5% Zn, 6.0% Pb and 235 g/t Ag — sits materially above those global averages. For investors assessing the asset, that grade premium is the key point: a sub-deposit running well ahead of the overall resource on every major metal is a meaningful quality signal within a larger mine plan.
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Ore Reserve estimate and development on the near-term horizon
Two concrete milestones now define the near-term path forward for Endeavor:
- An Ore Reserve estimate covering all Endeavor orebodies has commenced and is expected to be published in Q2 FY27.
- Development to potential supergene mineralisation has been designed and is expected to commence shortly.
That development access serves a dual purpose. It provides the underground exposure needed to reach the high-grade Upper Main Lode sulphide resource, and it will simultaneously expose the oxidised zone, enabling progressive face sampling and the potential identification of direct shipping ore as mining advances.
The Ore Reserve estimate will be a key derisking milestone for the project. Converting the expanded Mineral Resource into a formal mine plan gives investors a quantified basis on which to assess production potential, mine life, and project economics — a step that moves the Endeavor Mine from resource definition toward operational planning.
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