PolarX uncovers massive sulphide zone outside Caribou Dome copper resource

Caribou Dome hosts an MRE totalling 7.2Mt at 3.1% Cu and 1.6g/t Ag, with the system open along strike and at depth.

Two extension holes about 60m west of the resource have intersected previously unidentified overthrust units before entering visually observed copper sulphide mineralisation.

Hole CD26-009 intersected a 57.5m zone of massive to semi-massive sulphides from 138.9m with visible chalcopyrite occurring within very fine-grained calcareous shale.

Hole CD26-013 served up five zones of massive and semi-massive sulphides and hydrothermal breccia replacement mineralisation totalling 35.4m.

Assays from the two holes are pending.

The latest drilling stems from PolarX’s (ASX:PXX) 2026 exploration campaign at Caribou Dome, which forms part of its broader Alaska Range JV with Northern Star Resources (ASX:NST).

The program is expected to run through to the end of September and is fully funded by Northern Star.

Seventeen holes totalling 4980m have been completed as part of the 2026 Caribou Dome campaign, with significant visual massive sulphide intercepts identified.

The company said drilling to date had improved and extended its geological and structural understanding of the known mineralisation.

It had also identified mineralisation styles not previously encountered at Caribou Dome.

These include copper sulphide replacement of hydrothermal breccia clasts, which PolarX believes may indicate a feeder zone to the broader Caribou Dome copper system.

Replacement-style mineralisation was observed within hydrothermal fault breccias in hole CD26-013 at 284.6m to 285.6m, 291.3m to 294.4m and 304.2m to 305m.

PolarX interprets these findings as potential replacement of original calcareous layers, with the mineralisation progressing into finely laminated beds of alternating chalcopyrite and pyrite.

The company said drilling has also improved its exploration model for Caribou Dome and could lead to further discoveries elsewhere at Alaska Range.

The Alaska Range tenure is divided into the Caribou Dome and Stellar project areas.

The Stellar property sits directly northeast of Caribou Dome and features the Zackly resource, which totals 4Mt at 1.6g/t Au, 1.1% Cu and 12.6g/t Ag.

Northern Star is committing up to US$39 million over five years to earn a 70% stake in Alaska Range under the JV.

The funding is aimed at fast-tracking resource growth at Caribou Dome and Zackly, whilst unlocking the project’s regional exploration potential.

Northern Star has contributed US$11m to exploration programs during the 2025 and 2026 field seasons, earning an initial 30% project interest.

Exploration drilling in the western extension zone of Caribou Dome is continuing, with another 2000m of drilling on the cards.

PolarX believes that further success with the drill bit could significantly lift the current MRE at Caribou Dome.

Core from the holes drilled so far is being logged, cut and sampled, with initial assays expected this month.