Polymetals Confirms HighGrade Silver Intact Beyond 1996 Endeavor Collapse Zone

Underground drilling validates intact mineralisation adjacent to historic collapse zone

Polymetals Resources has completed the first 12 holes of a 34-hole underground diamond drilling campaign at the Endeavor Mine, confirming high-grade silver-lead-zinc mineralisation remains intact in the Upper Main Lode. Review of historical mine records suggests the area affected by the 1996 ground failure may be materially smaller than previously interpreted.

The drilling programme has returned 11 of 12 holes with significant mineralisation, totalling 713.6 m of a planned 3,100 m campaign. The mineralisation sits adjacent to existing mine development and infrastructure, eliminating the need for greenfields capital expenditure to access the target zone.

This drilling campaign represents potential upside to Endeavor’s mining inventory without requiring new infrastructure development — mineralisation is accessible from existing underground workings.

Best assay results deliver standout silver-lead-zinc grades

The first batch of assays has delivered consistent high-grade intercepts across the drilling programme, with 11 of 12 holes returning significant mineralisation. The results demonstrate broad widths combined with robust silver equivalent grades exceeding 400 g/t in multiple holes.

Key intercepts include:

• 45.2 m @ 436 g/t AgEq (197 g/t Ag, 8.9% Zn, 11.0% Pb, 0.18% Cu) — POL009
• 33.0 m @ 439 g/t AgEq (209 g/t Ag, 9.9% Zn, 8.1% Pb, 0.17% Cu) — POL002
• 33.0 m @ 408 g/t AgEq (205 g/t Ag, 9.6% Zn, 5.5% Pb, 0.14% Cu) — POL010
• 24.5 m @ 473 g/t AgEq (207 g/t Ag, 12.2% Zn, 6.8% Pb, 0.35% Cu) — POL007
• 26.7 m @ 439 g/t AgEq (227 g/t Ag, 9.3% Zn, 7.1% Pb, 0.16% Cu) — POL011
• 14.9 m @ 494 g/t AgEq (304 g/t Ag, 8.5% Zn, 5.9% Pb, 0.16% Cu) — POL008

What is silver equivalent and why does it matter?

Silver equivalent (AgEq) is a standardised measure that converts all metals in a polymetallic deposit into a single comparable figure. This allows investors to assess the overall grade quality of an intercept without manually comparing multiple metal values across different price points.

The calculation is based on metal prices (US$62/oz silver, US$3,500/t zinc, US$13,600/t copper, US$1,950/t lead) and metallurgical recoveries (80% silver, 89% zinc, 85% copper, 85% lead). Gold is not included in the AgEq calculation as some assays are still awaited.

AgEq grades in the 400-500 g/t range represent robust polymetallic mineralisation that could support economic extraction, particularly where existing infrastructure reduces development costs.

Executive Director outlines strategic significance

Executive Director Jess Oram highlighted the reinterpretation of the collapse zone extent and the proximity of the mineralisation to existing infrastructure as key factors supporting the drilling campaign’s strategic value.

Jess Oram, Executive Director

“Our reassessment of historical mine records and new drilling suggest the extent of the 1996 stope collapse may have been considerably smaller than previously interpreted.

“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.

“What makes these results particularly important is their location. The mineralisation occurs within an established mining environment, close to existing infrastructure and immediately adjacent to the high-grade Upper North Lode.”

Oram emphasised the location advantage: “What makes these results particularly important is their location. The mineralisation occurs within an established mining environment, close to existing infrastructure and immediately adjacent to the high-grade Upper North Lode.”

Historic collapse zone may be smaller than previously assumed

The 1996 stope collapse at the Upper Main Lode led to this area being considered largely sterilised for future mining. However, recent review of historic mine records, survey data and underground inspection suggests the affected area may be materially smaller than historic assumptions indicated.

This reinterpretation creates the opportunity to define substantial volumes of in-situ mineralisation that remain intact adjacent to the collapse boundaries. The drilling programme is designed to delineate the edge of the collapse zone and assess geotechnical conditions within the target volume.

If the collapse zone is confirmed to be smaller than historic assumptions, Polymetals may be able to convert a meaningful volume of known mineralisation into mineable inventory, representing potential resource upside at the existing operation. This is not new mineralisation discovery but rather recovery of previously written-off inventory potential.

Location advantages support potential mining pathway

The mineralisation occurs within an established mining environment, with existing underground development providing access to the target zone. The Upper Main Lode sits immediately adjacent to the high-grade Upper North Lode, which has supported recent production at Endeavor.

Location factors:

• Upper Main Lode — adjacent to Upper North Lode
• Existing underground development — provides access to target zone
• Proximity to infrastructure — mill, ventilation, power and haulage already in place

Infrastructure proximity significantly reduces the capital and time required to potentially bring this mineralisation into production compared to developing a new mining area. The mineralisation is accessible from existing underground development.

Drilling campaign continues with 22 holes remaining

The 34-hole campaign for approximately 3,100 m is designed to improve geological confidence, assess continuity of mineralisation and support evaluation of potential future mining opportunities within the Upper Main Lode area.

Programme status:

• Total programme: 34 holes, approximately 3,100 m
• Completed: 12 holes, 713.6 m
• Remaining: 22 holes

Some gold assays are still awaited and will be reported separately. The remaining drilling will focus on defining the scale and continuity of mineralisation across the reinterpreted collapse zone boundary.

Next steps:

1. Complete remaining 22 diamond drill holes
2. Receive outstanding gold assays
3. Define scale and continuity of mineralisation
4. Evaluate potential mining opportunities within Upper Main Lode

What this means for the Endeavor investment case

Endeavor holds an underground mineral resource of 16.3 Mt at 8.0% Zn, 4.5% Pb, 84 g/t Ag. This drilling campaign targets potential additions to mining inventory at the flagship operation, leveraging existing infrastructure and mine development.

The Upper Main Lode mineralisation represents organic growth potential at an established mine rather than exploration risk at a greenfields project. Successful conversion of this mineralisation into mining inventory would provide operational upside leveraged to the current favourable silver and zinc price environment.

The drilling results validate the reinterpretation of the collapse zone extent and confirm high-grade mineralisation remains intact in areas previously considered sterilised. If the remaining 22 holes continue to deliver similar grades and widths, Polymetals may be able to define a material addition to Endeavor’s future mining inventory without significant infrastructure investment.

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