Polymetals Resources Ltd has updated the global in-situ Mineral Resource estimate for the Endeavor mine in Cobar, New South Wales, bringing its total inventory to 20.7 million tonnes grading 7.5% zinc, 4.2% lead, and 82 g/t silver at a 5% Pb + Zn cut-off.

The revised total compares with the company’s previous May 2023 estimate of 16.3 million tonnes at 8.0% zinc, 4.5% lead, and 84 g/t silver. Despite ongoing mine depletion and the adoption of a more conservative 5% lower density assumption, the update expands total resource tonnage and increases contained silver from 44.0 million ounces to 54.3 million ounces. Total contained base metals now stand at 1.55 million tonnes of zinc and 0.86 million tonnes of lead.

The estimate incorporates 29 new drillholes, resurveyed historical workings, and mine depletion up to 31 July 2026. This follows the company's full consolidation of the asset on 31 July 2026, when it completed the acquisition of Cobar Infrastructure Pty. Ltd. and discharged vendor security.

Targeted underground diamond drilling within the Upper Main Lode successfully converted historical concepts into inventory by testing the 1996 subsidence zone, proving the affected footprint was smaller than previously mapped. The Upper Main Lode now accounts for 1.6 million tonnes at 8.5% zinc, 6.0% lead, and 234 g/t silver adjacent to existing mine infrastructure.

“The Upper Main Lode is proof that this approach works. We developed a new geological interpretation, drilled it systematically and have now converted that concept into additional Mineral Resource. Importantly, the global Endeavor Resource has also grown despite mining depletion and the adoption of more conservative density assumptions.” — Jess Oram, Executive Exploration Director

With the updated geological and resource model established, the company is preparing to complete detailed mine planning, geotechnical assessments, and a formal Ore Reserve estimate for the Upper Main Lode. Polymetals also plans to report outstanding assay results from drilling completed after the data cut-off date.

Read the full announcement: Endeavor Mine 2026 Mineral Resource