Caribou Dome Project

Caribou Dome Copper Project

The Caribou Dome Project comprises 216 contiguous State Mining Claims and is located immediately adjacent to the Company’s Stellar Project. The claims cover a total area of 116~Km2. The Caribou Dome project comprises 2 key areas:

  • Caribou Dome – earning 80% – An un-mined JORC resource open in all directions
  • Senator Extensions – earning 90% – a recently discovered 5x5km soil anomaly grading up to 12.1% copper in rock chips.


For more information and diagram of claims please refer to our ownership page


The Caribou Dome Project is located approximately 250km northeast of Anchorage. It is easily accessible by road; the Denali Highway passes within 20km of the project and from there a purpose built road provides direct access. The Anchorage-Fairbanks railway line is located approximately 100km west of the project. Any potential concentrate or metal produced from the project could be transported by road to the railway at Cantwell for shipment from the ports of Anchorage, Seward (all year) or Port Mackenzie. There are 2 nearby hunting lodges along the Denali Highway which provide accommodation facilities, communications, logistics support and supplies.


Copper mineralisation was first discovered at Caribou-Dome in 1963. From then to 1970 some 95 diamond holes were drilled to delineate 9 lenses of volcanic sediment hosed copper/silver mineralisation over approx. 800m of strike.

Significant additional drilling has since been undertaken by PolarX since 2015, with a maiden resource announced on 16 April 2017 which was substantially upgraded to include PolarX’s subsequent drilling, test work and structural interpretation on 13 June 2023.

Technical Review

Caribou-Dome occurs in deformed lenses of very fine-grained massive sulphides comprising chalcopyrite and pyrite associated with calcareous volcanic argillites of andesitic affinity. Mineralisation has been deformed by two phases of folding and subsequently faulted. The mineralisation extends from surface to depths of over 300m.

During early 2015, a comprehensive technical review of historic geological, geochemical and geophysical data was undertaken to prioritise targets for follow-up and to plan suitable exploration programs to optimally delineate additional high grade mineralisation. The results were as follows:

  • Multiple high-priority exploration targets are evident over more than 15km of strike. Outcrops of sediment-hosted copper mineralisation had previously been identified across the project, confirming the drill-tested mineralisation could be part of a much larger mineralised system
  • Two exceptional targets, both of which are completely untested by drilling, were identified. The first is outcropping mineralisation at Lens 2 that is 200m long, up to 15m wide and coincides with a 350m-long IP anomaly. The second is a 400m-long soil anomaly with assays up to 0.63% Cu, and coincident IP anomaly, immediately south of the known lenses
  • Additional drilling is warranted to evaluate the strike and depth extensions of all nine known mineralised lenses
  • Numerous extensive soil anomalies over 3.5Km of previously sampled strike required further exploration. These included four high-priority and three second order targets

Exploration Results

The first two holes drilled by PolarX at Caribou Dome (at the Lens 6 area) produced immediate success, with intersections of 10.1m at 7.1% Cu from 39.0m and 12.2m at 3.2% Cu from 39.8m respectively. These results confirmed that substantial thicknesses of shallow, high grade copper mineralisation are present at Caribou Dome. The results were comparable with previous adjacent drilling results, providing confidence in the reliability of the historic data.

  • 18.1m at 9.34% copper from 22.7m (DH9)
  • 18.4m at 6.25% copper from 31.4m (DH39)
  • 15.4m at 7.01% copper (DH93U)
  • 13.1m at 7.20% copper from 15.8m (DH40)
  • 11.0m at 8.20% copper from 29.0m (DH41)
  • 10.4m at 7.94% copper from 14.0m (DH37)
  • 12.8m at 5.78% copper (DH51U)
  • 13.0m at 4.94% copper (DH91U)
  • 9.1m at 6.97% copper from 28.7m (DH43)
  • 10.2m at 6.23% copper from 46.6m (DH32)
  • 12.2m at 5.04% copper from27.1m (DH32)
  • 10.7m at 4.99% copper from 18.0m (DH15)
  • 10.2m at 4.96% copper (DH70U)
  • 8.3m at 6.07% copper from 77.7m (DH44)

Thick copper mineralisation was intersected in the first two exploration holes drilled to test primary mineralisation beneath 200m of mineralised outcrop at Lens 2. Assay results included 8.7m at 1.7% Cu from 54.3m and 10m at 1.6% Cu from 62.5m. New IP data showed that these holes were drilled directly above a strong IP anomaly that was to be drill-tested.

A further hole drilled deep enough to begin evaluation of the 250m-long strong IP anomaly at Lense 2 intersected high-grade copper mineralisation including 3.4m at 4.8% Cu and 3.5m at 1.9% Cu.

A hole drilled at Lens 4 produced a spectacular intersection of thick, shallow, primary high-grade copper mineralisation, in total comprising 51.1m (estimated true thickness of ~25m) at 5.3% Cu from 4.4m. This result included 2.3m at 17.1% Cu from 4.4m, 14.1m at 10.6% Cu from 10.7m, 3.3m at 9.0% Cu from 39.8m and 3.2m at 9.6% Cu from 52.3m.

Mineral Resources

On 13 June 2023, PolarX announced a substantial increase in Mineral Resource estimate for Caribou Dome.

2023 Caribou Dome Mineral Resource estimation summary table.

Category Tonnes (Mt) Cu (%) Cu (t) Ag (g/t) Ag (oz)
Measured 1.0 3.9 39,800 8.6 284,000
Indicated 3.2 3.3 105,175 6.5 662,800
Inferred 3.0 2.6 79,400 5.7 552,000
Total 7.2 3.1 224,375 6.5 1,498,800

Reported at 0.5% Cu cut-off grade.

All Mineral Resource estimates are constrained within wireframes encapsulating the ore lenses. Estimated numbers may not add up exactly due to rounding.
Table reported at 100% recovery (ie, in-situ).

The revised Mineral Resource Estimate for Caribou Dome has a copper metal content of 224,375 tonnes. This was 2.6 times greater than the 2017 Mineral Resource Estimate of 2.8Mt at 3.1% Cu with contained copper metal of 86,000 tonnes (also using a 0.5% Cu cut-off, see ASX announcement 5 April 2017).

This substantial resource increase is expected to commensurately enhance PolarX’s recent Positive Mining Scoping Study on its Alaska Range Project as announced to ASX on 17 October 2022.

Silver has also new been estimated for the first time at Caribou Dome with a contained silver metal content of 1.5 Moz within the 0.5% copper cut-off envelope. The silver content is expected to further enhance the updated Scoping Study.

A strong indicator of the depth potential is that the second deepest hole drilled to date, which reached a depth of 280m from surface, recorded an intersection (not true width) of 15.4m at 7% Cu. PolarX’s most recent drilling intercepted 19.1m @ 7% copper and 11.2g/t silver.

Background to the Project

Copper mineralisation was first discovered at Caribou Dome in 1963. Almost all the exploration was undertaken at the Project between 1964 and 1970. Nine lenses of outcropping mineralisation were delineated over approximately 750 metres of strike. However, virtually all work was focused on only three of these lenses with a view to developing a small high-grade underground mine. Approximately 1,000 metres of underground workings were developed on two levels (an adit and a decline). In addition, more than 6,000m of diamond drilling (43 diamond core holes drilled from surface and 48 diamond core holes drilled from underground) were completed, together with 3,282m of underground percussion drilling.

The top 14 intersections produced copper grades ranging from 4.9% to 9.3% over intersected widths ranging from 8.3m to 18.4m. Cross sections and longitudinal sections indicate that mineralisation is mainly confined to sub-vertical lenses of good thickness. The drilling did not constrain the extents of mineralisation at any of the known lenses.

Other than for PolarX commencing 2015, little work had been undertaken since 1970. A further 17 surface diamond holes were drilled; nine shallow holes were drilled in 2011 to evaluate lenses 7 and 9, six of which intersected copper sulphide mineralisation. A 225kg bulk sample for metallurgical test work was collected in 2008.


Copper mineralisation at the Caribou Dome Project is predominantly stratiform. Historically, nine outcropping lenses of high-grade pyrite-chalcopyrite mineralisation were delineated over approximately 750m of strike. These are predominantly located in argillites at an interface with a sequence of volcanic rocks. Interbedded limestones appear to have exerted an important control on the location of mineralisation.


  • 2015 and 2016 testwork on the Caribou Dome Central deposit completed on a 5.03% composite sample yielded over 95% Cu recoveries and a concentrates grading up to 24.5% Cu were produced.
  • 2016 testwork on a sample grading 7.4% from the extended Lens 7/8 Area at Caribou Dome recovered over 99% Cu and concentrates up to 27.4% Cu were produced.
  • Testwork to date has found that high copper recoveries at Caribou-Dome deliver a relatively low concentrate grade.
  • Optimisation testwork therefore continues with the aim of increasing copper/silver recovery and improving concentrate grades.
  • More optimisation work is also warranted at Zackly to increase free gold recovery.

Senator Discovery (90%)

  • First discovered during 2016 extension program
  • Lies between Caribou-Dome and Zackly deposits.
  • Extensive gossans in a 5km long copper in soil anomaly.
  • Up to 12.1% Cu in surface rock chips.
  • No previous geophysics or drilling
  • IP survey, mapping and sampling in 2017
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