Western Mines Group (ASX: WMG) has unveiled more broad nickel sulphide zones at its Mulga Tank nickel project near Lake Minigwal in Western Australia after assays were returned from its latest phase-three drilling campaign within the intriguing ultramafic complex at the site.
The company launched its 23-hole program early in July to infill around a previous hole of interest in the high-grade core of its grid and to extend the grid at its eastern and southern margins. By early this month, it revealed it had bored through 6002m of drilling to complete the first 19 holes of the program.
Management has today revealed that the first batch of results to come back from the laboratory show that all four of the holes contain broad zones of nickel sulphide mineralisation, with elevated nickel and sulphur closely associated with anomalous copper and the combined platinum group elements (PGE), platinum and palladium.
Comparing the four holes shows their nickel values sitting tightly in the range between 0.27 to 0.29 per cent and cobalt values seem to be welded between 129 parts per million and 133ppm. Copper also ranges closely between 62ppm and 96ppm, while PGE values run between 14 parts per billion and 23ppb.
Nickel-cobalt-copper sulphide deposits are typically associated with mafic and ultramafic intrusive rocks and are characterised by the presence of nickel, cobalt, and copper sulphide minerals. Such deposits can occur as disseminated sulphides in the host rock, or as discrete ore bodies and are often found associated with other valuable minerals such as PGEs.
We are looking to target shallow higher-grade zones around 0.40% Ni that could form areas for starter pits in a mine model. A relatively flat-lying zone around this depth can be traced fairly extensively across eight holes. A regular flow of assay results is expected from the Phase 3 program throughout this month.
Western Mines Group Managing Director Dr Caedmon Marriott
The company’s latest results exhibit robust intersections of disseminated nickel sulphide mineralisation, with downhole intervals of more than 200m containing high sulphur-to-nickel ratios. In addition, abundant chalcophile-suite elements, including copper and PGEs, clearly demonstrate strong mineralisation down all four holes.
While the nominal target depth was 360m, one hole was drilled to 438m, where visible sulphide mineralisation was observed. All the latest four relatively deeper holes – when contrasted with the previous drill programs – all ended in mineralisation.
The previous hole of interest at Mulga Tank produced a run of 38m at 0.44 per cent nickel and 174ppm cobalt from 159m including 13m at 0.53 per cent nickel and 208ppm cobalt from 183m.
Western Mines says a relatively coherent, flat-lying zone of higher-grade nickeliferous material has come to light around a depth of between 150m and 200m and it has now been proven by drilling across several holes in the central core zone.
Successfully identifying extensive shallow nickel mineralisation at a nominal tenor around 0.4 per cent nickel would be significant because it could yield a potentially open-pittable resource. That resource could become a solid foundation to kick off initial mining operations and generate useful cash flow, while ongoing drilling and modelling of a deeper exploitable – and likely sulphidic – resource continues.
Analytical results are yet to come back from three holes in the eastern margin of the central core area grid and also from the holes in the remainder of the program. Five other scout regional holes are also planned for about 5000m to test the interpreted komatiite channels to the north-west of the main body of the complex.
In other work, results from a downhole electromagnetic (DHEM) survey undertaken in August have also identified anomalies associated with the visible sulphides logged in each of the holes. Results from two of the holes are being reviewed and may lead to more drilling to bore through end-of-hole anomalies.
Remaining core from the company’s third exploration incentive scheme diamond hole is also being transported to Kalgoorlie for cutting and sampling.
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