Polymetals Proves 1996 Mine Collapse Left High-Grade Silver Ore Intact
Underground drilling confirms high-grade silver-lead-zinc mineralisation at Endeavor Mine
Polymetals Resources has announced encouraging results from underground diamond drilling at its Endeavor Mine in the Cobar Basin, New South Wales. The programme has confirmed broad zones of high-grade silver-lead-zinc mineralisation remain intact in the Upper Main Lode, an area previously considered largely sterilised following a 1996 ground collapse event.
The company has completed the first 12 of 34 planned diamond holes (713.6 m of approximately 3,100 m total programme), with 11 of 12 holes returning significant mineralisation. A review of historical mine records, survey data and underground inspection indicates the area affected by the 1996 ground failure may be materially smaller than previously interpreted, creating the opportunity to define substantial volumes of in-situ mineralisation which remain intact.
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Best assay results from initial drilling programme
The standout intercepts demonstrate both grade and width, with results presented using silver equivalent (AgEq) as the primary metric for comparison. These intersections occur adjacent to interpreted collapse boundaries and near existing infrastructure, enhancing the potential to convert this area into mining inventory.
| Hole ID | Interval (m) | Silver (g/t) | Zinc (%) | Lead (%) | AgEq (g/t) |
|---|---|---|---|---|---|
| POL009 | 45.2 | 197 | 8.9 | 11.0 | 436 |
| POL002 | 33.0 | 209 | 9.9 | 8.1 | 439 |
| POL010 | 33.0 | 205 | 9.6 | 5.5 | 408 |
| POL007 | 24.5 | 207 | 12.2 | 6.8 | 473 |
| POL011 | 26.7 | 227 | 9.3 | 7.1 | 439 |
| POL008 | 14.9 | 304 | 8.5 | 5.9 | 494 |
Wide intercepts with consistent high grades across multiple holes indicate mineralisation continuity rather than isolated pockets.
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 one comparable unit. Endeavor is a polymetallic deposit containing silver, zinc, lead and copper, and AgEq allows investors to compare intercepts that contain different metal ratios.
AgEq calculation uses assumed metal prices and metallurgical recovery rates. Polymetals’ assumptions are: US$62/oz silver, US$3,500/t zinc, US$13,600/t copper, US$1,950/t lead. Recovery rates applied are 80% silver, 89% zinc, 85% copper, 85% lead.
Understanding AgEq helps investors assess whether drilling results are genuinely high-grade or inflated by calculation assumptions. Polymetals’ assumptions are disclosed and can be benchmarked against current spot prices.
Why the 1996 collapse zone reinterpretation matters
A ground failure during previous mining operations in 1996 led to an area being considered largely sterilised. Polymetals’ review of historical mine records, survey data and underground inspection suggests the affected area may be materially smaller than previously interpreted.
11 of 12 holes intersected significant mineralisation, supporting the reinterpretation thesis. The mineralisation occurs within an established mining environment, close to existing infrastructure and immediately adjacent to the high-grade Upper North Lode.
If the collapse zone is indeed smaller than historically assumed, substantial tonnes of high-grade material previously excluded from mine planning could potentially be brought back into the mining inventory.
Executive commentary
Jess Oram, Executive Director, Polymetals Resources
“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.”
Drilling programme status and next steps
Assay results received to date from the first 12 NQ diamond drillholes have provided sufficient encouragement for Polymetals to continue the underground drilling programme. The programme is designed to improve geological confidence, assess continuity of mineralisation and support evaluation of potential future mining opportunities within the Upper Main Lode area.
- Total programme: 34 NQ diamond drillholes for approximately 3,100 m
- Completed to date: 12 holes (713.6 m)
- Remaining: 22 holes
The decision to continue drilling signals management confidence in the early results. Completion of the full programme will determine whether this area can meaningfully contribute to Endeavor’s future production profile.
Endeavor Mine resource base
The Upper Main Lode drilling represents potential upside to Endeavor’s current resource and reserve base. Any successful conversion of Upper Main Lode mineralisation would add to an already substantial resource base at a mine with existing infrastructure and processing capability.
| Category | Tonnes (Mt) | Zinc (%) | Lead (%) | Silver (g/t) |
|---|---|---|---|---|
| Underground Mineral Resource (JORC 2012) | ||||
| Total | 16.3 | 8.0 | 4.5 | 84 |
| Stage 1 Ore Reserve (JORC 2012) | ||||
| Total | 6.6 | 4.32 | 2.04 | 73 |
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Investment outlook
The drilling programme represents a relatively low-cost opportunity to potentially expand Endeavor’s mineable resource base using existing infrastructure. The potential to recover previously written-off high-grade mineralisation, combined with the infrastructure advantage of mineralisation adjacent to existing development, positions this as a material opportunity for the company.
Upcoming catalysts include:
- Some gold assays from current holes still pending
- 22 additional holes to be completed in current campaign
- Results will inform whether Upper Main Lode can be added to mining inventory
The drilling programme’s success in confirming broad zones of high-grade mineralisation suggests substantial volumes of in-situ material remain accessible from existing underground development.
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