White Cliff Minerals (ASX: WCN) has unveiled extensive evidence of chalcocite-dominant, copper-rich vein systems along big strike distances after maiden field work at its Rae project in the Canadian province of Nunavut.
The company has reported significant – sometimes spectacular – hard surface evidence of the red metal at its PAT, HALO, Cu-TAR, DON CALMAL and Kilauea targets, with abundant native copper observed at surface in the latter.
White Cliff appears to have grabbed a major first-mover advantage in the locality, getting its foot on premium ground last year ahead of a major land-rush in the broader Nunavut-Coppermine area in the past six months.
The field program included returning to and sampling historic copper sites, resulting in important expansions to the strike of surface copper mineralisation at every site the company visited.
The outcropping copper mineralisation throughout the project area is visually stunning and exceeds expectations. The focus of our maiden field program across both Nunavut and Great Bear Lake has been twofold. Firstly, to confirm decades old historical state survey results from multiple project locations and extend the observable strike of each and in parallel undertaking airborne geophysics to further refine these targets. Second is to prioritise and prepare project areas for drilling.
White Cliff Minerals managing director Troy Whittaker
That strategy is exemplified by the company’s extension of its PAT target to more than 400m of outcropping, semi-massive, quartz and carbonate vein-hosted chalcocite-bornite mineralisation in metre-scale boulder floats along a traceable north-east/south-west trend. The trend coincides with a topographic rise – possibly due to greater quartz resistance to erosion – from which the company infers a possible source beneath cover about 2m to 40m off to the west.
Management has also mapped and sampled the HALO vein system out to more than 440m of strike and it features abundant malachite, azurite and chrysocolla copper secondary mineralisation, spiced up with occasional native copper. The HALO mineralisation lies within a north-south-trending sub-vertical structure cutting through stacked basalts of the Coppermine River Group.
The identification of high-grade copper in samples of fine-medium-grained sandstone containing sheeted chalcocite veining along bedding planes at HALO, provides an important clue to sediment-hosted mineralisation origins and greatly enhances the target’s potential prospectivity and likely tonnage-scale.
At White Cliff’s Cu-TAR target where massive sulphide mineralisation outcrops within a topographic low over 388m, historical reports refer to quartz-carbonate-chalcocite veining. Although the company did not undertake comprehensive sampling along the copper trend, the field team was able to collect 18 samples of chalcocite-mineralised quartz-carbonate veining across four separate structures.
“Vein 2” was sampled along 30m of strike before being obscured by surface cover. The veins were noted as being sub-vertical and striking between north-east and east-west, while mineralisation thickness noted at surface varies between a veined zone with 0.5m wide individual veins and a breccia zone up to 4m thick.
The southernmost “Vein 4” of those structures was sampled along 338m of strike and was observed to host intervals of massive chalcocite.
At the DON target, a total of 18 samples were taken, while mapping and sampling revealed three quartz-carbonate-chalcocite-bornite veins hosted in Coppermine River basalts, with both north-south and east-west main vein orientations evident and individual veins being traceable for more than 200m, varying in thickness from 0.5m to 2m.
At the CALMAL target, field personnel encountered chalcopyrite-chalcocite-malachite veining and breccia in fine-medium-grained sandstones of the basal Rae Group sediments. It is evidence that copper-bearing hydrothermal fluids reached the sediments of the basal Rae Group and points to potential for reduced-facies type sediment-hosted copper deposits – although such deposits could be lower in the stratigraphy than the sandstones exposed at the surface.
The Kilauea target presents yet another style of mineralisation at the Rae project, as evidenced by the stacked massive basalts with brecciated and vesicular flow tops of the Copper Creek basalts that dip gently northwards. The flow tops exhibit chalcocite-malachite-chrysocolla-native copper mineralisation that infills the basalt vesicles.
To date, the field team has identified about 120m of mineralised basalt flow top mineralisation.
White Cliff’s Rae project hosts all the required first-order controls to produce a sedimentary-hosted copper deposit, including copper source, transport agent, pathways, reduction-oxidation boundary, reactive host rocks and proof-of-concept.
Additionally, the company points out that the mineralisation style has been de-risked by Kaizen Discovery’s 2015 drilling results where one hole intersected 28.97m of 0.57 per cent copper from 197.03m hosted within the basal Rae Group sediments.
Management has also completed its MobileMT airborne geophysical survey at Great Bear Lake, on time and on budget and expects the survey work at Rae to be completed within the next five to 10 days.
In all, first-mover advantage in a target rich-environment with a healthy range of potential mineralisation styles seems to be a good recipe for White Cliff to run with.
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