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Western Mines adds new chapter to Mulga Tank nickel tale

Updated: Apr 30

Western Mines diamond core drilling at Mulga Tank Credit: File

Western Mines continues to build its compelling nickel story at its Mulga Tank project near Kalgoorlie in Western Australia after revealing broad zones of shallow disseminated and semi-massive nickel mineralisation in three new reverse-circulation (RC) holes.

The company’s latest results reveal long intercepts up to a cumulative 220m at 0.28 per cent nickel and matrix-to-semi-massive sulphides, with a 1m sample running 1.84 per cent from 293m. It says the zones with elevated nickel and sulphur correlate with highly-anomalous copper and combined platinum group elements (PGE), platinum and palladium.

The first holes yielded a cumulative intercept of 209m at 0.28 per cent nickel, 129 parts per million cobalt, 381ppm copper, and 18 parts per billion PGE. The second hole gave up a remarkably similar cumulative run of 186m at 0.28 per cent nickel, 135ppm cobalt, 78ppm copper and 22ppb PGE from 90m.

The third hole repeats the geological mimicry, with a cumulative run of 220m at 0.28 per cent nickel, 132ppm cobalt, 112ppm copper and 18ppb PGE, confirming the uniformity of depth and mineral tenor in this remarkable, thick disseminated horizon.

The extensive Mulga Tank mineral system keeps on giving and results from our initial wide spaced RC drilling program continue to build an exciting new dataset to begin to better understand it and help vector further drilling. It’s very encouraging, if not incredible, that all 14 holes received to date have contained broad intervals showing the geochemical signature of disseminated nickel sulphide mineralisation across the entire 2.5km length tested by the drilling. Western Mines Group managing director Dr Caedmon Marriott

Marriott said the shallow mineralisation is open in all directions and is not constrained by the company’s initial drilling.

The Mulga Tank nickel story is now being spiced up with new details almost twice weekly as runs of often spectacular assays now avalanche from the laboratory. Results have now been returned for 14 holes from the 22-hole, 7000m RC drilling program.

The campaign is the first systematic drilling of the Mulga Tank ultramafic complex and was designed on a broad grid spacing to cover the central area of the ultramafic dunite intrusive where Western Mines had previously sunk six deep diamond-core holes.

The program was tasked to unravel the story behind long strings of disseminated nickel mineralisation observed in the diamond core, which starts just below sand cover 60m-to-90m deep and often continues to vertical depths from about 250m to occasionally over 300m, with uniform thicknesses and grade.

That unusual occurrence had prompted thoughts of a potential shallow, disseminated Mount Keith style of nickel resource, which could be open-pittable.

The RC holes were spaced at about 500m by 300m and cover a 2500m-by-1000m area across the centre of the complex. Each hole was designed to a target depth of about 300m, which was achieved in all but three holes, for a total of 7035.5m.

About 60m of the top of each hole, amounting to a total of 1321m, was through sand cover that entailed mud-rotary drilling.

All holes were sampled at 1m intervals from the start of RC drilling – from the bottom of mud-rotary drilling – with a total of 5721 samples delivered to the laboratory for analysis.

Individual intercepts in the three holes continue the story. Quoting only nickel results for clarity, the first hole yielded 85m at 0.26 per cent nickel from 86m, including 2m at 0.54 per cent from 138m and 124m at 0.29 per cent from 188m, ending in mineralisation. The previous 124m run included 4m at 0.45 per cent nickel from 249m and included 6m at 0.57 per cent from 290m that also shows 1m at 1.84 per cent from 293m.

The second hole gave up an intercept of 186m at 0.28 per cent nickel from 90m including 1m at 0.6 per cent from 165m with 3m at 0.51 per cent from 229m. The third hole completed the nickel trifecta with 184m at 0.27 per cent from 72m, including 6m at 0.5 per cent from 133m that has 2m at 0.75 per cent from 134m.

Western Mines says high-grade results from the first hole confirm visual observations during logging of the presence of matrix-to-semi-massive sulphides, with a 1m sample running 1.84 per cent nickel, 0.10 per cent cobalt and 4.88 per cent copper. Moreover, management says about 45 to 70 per cent of the samples from all the holes to date show mineralisation with elevated nickel and sulphur, accompanied by highly anomalous cobalt, copper and PGE.

It adds that the uppermost zone of disseminated mineralisation seems to be laterally extensive and it is likely to extend well beyond the limits of the current RC drill pattern. That would be significant considering the RC program has already swept a total volume of about 650 million cubic metres of mostly mineralised rock in the centre of the main body, assuming about a 320m average drillhole depth and about 60m sand cover.

At this stage, Mulga Tank is not looking like just another story, but an opus that is gradually and inexorably building momentum. As more people watch it unfold, the more there are anxious to take in the denouement – that final part of a narrative in which the strands of the plot are drawn together and matters are explained or resolved.

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