Polymetals Unlocks High-Grade Silver Zones Written Off Since 1996 Ground Collapse

Polymetals confirms high-grade silver-lead-zinc mineralisation at Endeavor Mine

Polymetals Resources has confirmed that broad zones of high-grade silver-lead-zinc mineralisation remain intact in the Upper Main Lode at its Endeavor Mine in New South Wales, adjacent to a ground collapse zone previously thought to have sterilised the area. Underground drilling has returned 11 significant intercepts from the first 12 holes completed, validating the company’s reinterpretation that the 1996 collapse zone may be materially smaller than previously assumed. The mineralisation is located adjacent to existing underground infrastructure, enhancing potential for conversion into mining inventory.

The company has completed 12 of 34 planned holes (713.6 m of 3,100 m campaign) with 11 holes returning significant intercepts. This confirmation of intact high-grade mineralisation in an area written off for nearly three decades fundamentally changes the resource optionality at Endeavor.

What is the Upper Main Lode and why does it matter?

The Upper Main Lode is a historical production area at Endeavor that was partially sterilised by a ground collapse event in 1996. Industry-standard practice following such events is to model the affected zone conservatively — often larger than the actual failure — to protect worker safety and mine planning.

Polymetals’ review of historical mine records, survey data, and recent underground inspections suggests the collapse may have affected a materially smaller area than the conservative interpretation assumed. If true, this means significant volumes of high-grade ore remain in-situ and potentially mineable.

This is not exploration in greenfields; it is de-risked brownfields upside within an operating mine with existing infrastructure. The capital intensity to access this material is far lower than developing a new deposit.

Drill results return broad, high-grade intercepts

The first 12 holes have returned standout assay results. Results are reported in silver equivalent (AgEq) to allow comparison across the polymetallic mineralisation. The AgEq calculation incorporates assumed metal prices of US$62/oz silver, US$3,500/t zinc, US$1,950/t lead, and US$13,600/t copper, with metallurgical recoveries of 80% silver, 89% zinc, 85% lead, and 85% copper. Gold assays are not yet included in the AgEq figures as some results are awaited.

These grades compare favourably to Endeavor’s existing Mineral Resource, which averages 8.0% zinc, 4.5% lead, and 84 g/t silver. Confirmation of similar or higher grades adjacent to infrastructure supports the thesis that meaningful tonnes could be added to the mine plan.

Management commentary on the drilling programme

Executive Director Jess Oram emphasised that the results validate the company’s reinterpretation of the collapse zone and confirm substantial high-grade silver-lead-zinc volumes remain intact.

Jess Oram, Executive Director

“The results from the first 12 holes provide strong support for that view. Every hole (bar one) has intersected significant mineralisation demonstrating that substantial volumes of high-grade silver-lead-zinc remain intact adjacent to the collapse boundaries.”

Oram noted the mineralisation’s proximity to existing infrastructure and the high-grade Upper North Lode as key factors that enhance the potential for this area to be converted into future mining inventory.

What is silver equivalent and how should investors interpret it?

Silver equivalent (AgEq) is a standardised metric used to express polymetallic grades as a single comparable figure. Polymetals uses silver as the reference metal because silver is the dominant economic metal at Endeavor.

AgEq calculations incorporate assumed metal prices and metallurgical recoveries, not actual sale prices, so they should be used for comparison purposes rather than revenue forecasting. Gold assays are not yet included in the AgEq figures as some results are awaited.

AgEq allows investors to compare drill intercepts across different holes and against the broader resource base without needing to weight each metal manually.

Next steps and remaining drilling programme

The 34-hole, 3,100 m drilling campaign is continuing following encouraging results from the first batch. The programme is designed to improve geological confidence, assess mineralisation continuity, and support evaluation of potential future mining opportunities within the Upper Main Lode.

Further assays are pending for the first 12 holes (some gold results awaited), and additional results will be reported as the campaign progresses. The objectives of the programme are to:

1. Complete remaining 22 holes of the 34-hole campaign
2. Report outstanding gold assays from initial batch
3. Assess continuity and scale of mineralisation
4. Evaluate potential addition to Endeavor’s mining inventory

Continued drilling success could support a material addition to Endeavor’s mine life at low incremental capital cost given proximity to existing development.

Endeavor Mine resource base and production context

Endeavor’s existing Mineral Resource and Ore Reserve provide context for the potential upside from the Upper Main Lode. The underground Mineral Resource totals 16.3 Mt at 8.0% zinc, 4.5% lead, and 84 g/t silver, with a Stage 1 Ore Reserve of 6.6 Mt at 4.32% zinc, 2.04% lead, and 73 g/t silver.

Any tonnes converted from the Upper Main Lode drilling would be incremental to this existing resource base, potentially extending mine life or improving production optionality.

Don’t Miss the Next Mining Breakthrough

Join 20,000+ investors getting FREE breaking ASX news delivered within minutes of release, complete with in-depth analysis. Click the “Free Alerts” button at StockWire X to receive real-time alerts the moment market-moving announcements hit the ASX across mining, tech, healthcare, and finance sectors.