Polymetals Resources (ASX:POL) has increased the mineral resource estimate at its Endeavor Mine in New South Wales to 20.7 million tonnes (Mt), despite ongoing mining and the adoption of a 5% lower density assumption.
The global in-situ resource, excluding tailings, grades 7.5% zinc (Zn), 4.2% lead (Pb), and 82 grams per tonne silver (Ag) at a combined 5% lead and zinc cut-off.
It contains an estimated 1.55Mt Zn, 860,000 tonnes Pb, and 54.3 million ounces of Ag. The estimate comprises 5.9Mt measured, 11.1Mt indicated, and 3.7Mt inferred.
It is the first re-estimation of the entire Endeavor model since 2019. Compared with the 2019 estimate using the same cut-off, tonnage has increased from 20.1Mt to 20.7Mt.
The update incorporates 29 new drill holes and depletion to 31 July 2026. Polymetals mined 344,000 tonnes between June 2025 and July 2026, mainly from remnant areas around historical stopes.
Drilling at the Upper Main Lode added 1.3Mt of sulphide mineralisation previously interpreted to sit within the 1996 subsidence zone.
The company says the revised interpretation indicates the subsidence footprint is smaller than previously modelled.
The Upper Main Lode now hosts 1.6Mt @ 8.5% Zn, 6% Pb, and 234g/t Ag adjacent to existing underground development.
Executive Exploration Director Jess Oram says the result validates Polymetals’ decision to reassess historical interpretations.
“We developed a new geological interpretation, drilled it systematically, and have now converted that concept into additional mineral resource,” Oram says.
The updated model also incorporates rebuilt stope and development wireframes, corrected historical surveys, and revised upper-level stope interpretations.
Polymetals notes it reduced assumed densities by 5% following historical mine reconciliation and replaced the net smelter return reporting threshold used in 2023 with a grade-based cut-off. The company notes the change in cut-off limits direct comparison with the 2023 estimate.
About 63% of the resource lies within 5m of existing stopes or subsidence areas. Polymetals says recovery from some of this material may be constrained by local geotechnical conditions.
The company says it plans further mine planning and geotechnical assessment before preparing an ore reserve estimate for the Upper Main Lode. Outstanding assays and drilling across the overlying supergene zone may inform subsequent resource updates.
Oram says this work forms part of a broader exploration strategy at Endeavor.
“Polymetals’ growth strategy extends beyond the current Upper Main Lode program. Exploration has remained an active part of the Endeavor restart, initially focused on opportunities within and immediately surrounding the extensive mine infrastructure,” Oram adds.
“The company is now progressively broadening that effort across its wider exploration licences, including drilling on more distal targets.”
Polymetals Resources is a precious and base metals producer operating the Endeavor mine in NSW’s Cobar Basin.
Beyond the mine, the company controls 1,107km2 across the Northern Cobar Basin, where its exploration portfolio includes the Carpark, 4 Tank, Boundary Tank, Furney’s Tank, and Kiri prospects.
Write to France Pinzon at Mining.com.au
Images: Polymetals Resources
