PolarX Hits 57m Copper Zone 60m Beyond Caribou Dome Resource Boundary

Massive sulphides discovered 60m west of the Caribou Dome resource

PolarX (ASX: PXX) has intersected broad massive sulphide zones approximately 60m west of the existing Caribou Dome mineral resource boundary, materially extending the known footprint of the copper system. Two holes, CD26-009 and CD26-013, returned significant visual copper sulphide mineralisation in an area not previously captured by the current resource model.

Hole CD26-009 intersected 57.5m of massive to semi-massive sulphide with visible chalcopyrite, from 138.9m to 196m downhole, hosted within calcareous fine-grained sediments interlayered with minor gabbro and basalt. Hole CD26-013 cut five discrete zones of massive and semi-massive sulphides totalling 35.4m, with intervals at 179.9–190.2m, 199.4–205.8m, 217.63–231.07m, 284.9–293.2m, and 351.2–356.4m.

Both holes drilled through previously unidentified overthrust units into the chalcopyrite mineralisation. Replacement mineralisation of hydrothermal breccias was observed across multiple intervals in CD26-013, which the company’s geologists interpret as potentially indicative of feeder zones to the Caribou Dome copper system.

Important caution: The company explicitly notes that the massive sulphides are extremely fine grained, making visual recognition of copper sulphide species difficult. Visual estimates of mineral abundance are not a substitute for laboratory analysis. Assay results for CD26-009 and CD26-013 are anticipated in October 2026, and investors should treat current results as preliminary geological logging only.

The 2026 drilling campaign is fully funded by Northern Star Resources as part of the Alaska Range Joint Venture. 17 holes totalling 4,980m have been completed to date, with approximately 2,000m of planned drilling remaining. The campaign is expected to be complete by the end of September 2026, with initial assay results from other 2026 holes also expected that month.

What massive sulphide copper mineralisation means for investors

Intersecting mineralisation outside an established resource boundary is one of the more significant signals in copper exploration. To understand why, it helps to know what you’re actually looking at.

Understanding the Caribou Dome copper system

Caribou Dome is interpreted as a distal volcanic-hosted massive sulphide (VHMS) deposit. VHMS deposits form when hot, metal-rich hydrothermal fluids discharge onto the ancient seafloor or into surrounding sediments, precipitating dense sulphide minerals including chalcopyrite, which is the primary copper-bearing mineral. The result is layered, high-grade zones of copper sulphide that can extend over significant distances if the geological conditions are right.

At Caribou Dome, the mineralisation occurs as massive to semi-massive laminated sulphide layers associated with fine-grained calcareous sediments and andesitic volcanic rocks. The newly intersected breccia replacement style in the western zone is a distinct mineralisation type not previously encountered at the project — and one that PolarX’s geologists interpret as a potential feeder zone signature.

Why drilling outside the resource boundary matters

The existing Caribou Dome JORC resource sits at 7.2 million tonnes at 3.1% copper and 6.5 g/t silver, a high-grade deposit. That resource has been delineated over approximately 800m of strike and remains open below the current 300m resource depth.

Intersecting mineralisation 60m west of that boundary tells you the copper system extends beyond what the current geological model captures. Key points to keep in mind:

• Caribou Dome JORC resource (at 0.5% Cu cut-off): 7.2Mt @ 3.1% Cu & 6.5 g/t Ag (comprising 1.0Mt Measured at 3.9% Cu, 3.2Mt Indicated at 3.3% Cu, and 3.0Mt Inferred at 2.6% Cu)
• Copper mineralisation delineated over approximately 800m of strike, open below 300m depth
• Newly identified breccia replacement mineralisation interpreted as a potential feeder zone to the main copper system
• The 2026 drilling season has materially improved the geological and structural model for Caribou Dome

The company has stated that mineralisation in the western zone remains open at depth and along strike to the west — the standard framing for resource expansion potential. Whether the visual results translate into grade will only be confirmed once laboratory assays are received.

Northern Star-backed campaign targets resource expansion

This is not speculative junior exploration funded by a company burning its last cash reserves. The 2026 drilling program is fully funded by Northern Star Resources — one of Australia’s largest gold producers — as part of a structured earn-in arrangement under the Alaska Range Joint Venture.

Joint venture structure and funding

Northern Star can earn up to 70% in the Alaska Range Joint Venture over five years by making annual cash contributions totalling up to US$39 million. PolarX currently holds a beneficial interest of 60% in the Caribou Dome Project.

The Year 2 contribution of US$6 million was confirmed received on 30 April 2026, funding all of the current season’s exploration activities including the drill program and magnetotelluric (MT) survey. That ongoing funding participation signals institutional confidence in the project’s exploration upside.

What comes next — assays, ongoing drilling, and resource potential

The western extension zone is still being drilled, and the most important data is yet to arrive. Here are the near-term milestones investors should track:

1. Ongoing western extension drilling, with the campaign expected to complete by end of September 2026
2. Initial assay results from other 2026 holes, expected September 2026
3. Assay results for CD26-009 and CD26-013, anticipated October 2026
4. Potential for an updated mineral resource estimate following assay receipt and geological interpretation

The company has stated that exploration success in the western zone “could significantly boost the current mineral resource estimate” — though this is explicitly conditional on assay results confirming grade.

For context on what resource growth could mean at the project level, PolarX’s 2024 Scoping Study projected a pre-tax NPV of A$625 million (at a 7% discount rate), based on assumed copper and gold prices of US$8,500/t and US$1,900/oz respectively. It is important to note these figures are from a prior study based on the existing resource, and the current drill program is earlier-stage exploration. The scoping study metrics do not reflect the western extension results, which remain subject to assay confirmation.

The next two months represent a genuine inflection point for the Caribou Dome story. If the assays return grades consistent with the visual sulphide intensity logged in CD26-009 and CD26-013, the resource expansion case becomes significantly more concrete.

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