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Western Mines sets sights on open-pit nickel operation

Updated: Apr 30


A Blue Spec Drilling rig working for Western Mines Group. Credit: File

Western Mines Group is hot on the trail of potentially open-pittable disseminated nickel mineralisation in the weathered zone at its Mulga Tank project, east of Kalgoorlie in Western Australia – and it may yet form a key resource for a scoping study.


The company has expanded its planned 6600m reverse-circulation (RC) drill program to chase a shallow zone that lies above the main body at an average depth of between 60m and 70m under sand cover.


The RC program was initiated after management noted that the upper zones of earlier deep diamond drillholes, which had been put in to test the overall sulphide mineralisation potential and define the depth limits of the intrusive, clearly showed laterally continuous, weathered, disseminated nickel mineralisation across the top of the main body. It extended to a depth of about 250m to 320m from surface.


The RC program at Mulga Tank is progressing well and is rapidly testing the main central body of the Complex. We’ve expanded the initial 18-hole program, adding some additional holes on the eastern margin around hole MTD027 - the program now aims to test a ~2,500m x ~1,000m area. Each hole is taking around 1-2 days to complete so the program may be finished by early November. Western Mines Group managing director Caedmon Marriott

Mr Marriott also said the company’s work partner on the project, Blue Spec Drilling, had agreed to take $250,000 worth of shares, subject to shareholder approval, to fund a significant portion of the RC program.


Western Mines says the overall shallow nickel distribution is exemplified by its last deep diamond drillhole, which it describes as a “bit of a wildcat”. It is in the deepest part of the intrusive that encountered the dunite footwall at 1630.9m and intersected a cumulative 694m at 0.31 per cent nickel. But more importantly, the hole nailed three relatively shallow mineralised intercepts – 64m at 0.27 per cent nickel, 133 parts per million cobalt and 55ppm copper from 122m, 38m at 0.32 per cent nickel, 154ppm cobalt and 114ppm copper from 210m, and 30m at 0.34 per cent nickel, 157ppm cobalt and 112ppm copper from 290m.


While it is not a cohesive single intersection like its neighbouring diamond hole, which scored a continuous shallow nickel hit of 130m at 0.31 per cent nickel and 136ppm cobalt from 116m, management believes the three intersections comprise potentially open-pittable widths and realistic depths and collectively total a similar 132m interval.


Together with four other diamond holes, the shallow nickel mineralisation has now been proven to exist through some 3.2km across the complex and is thought to be worth exploring in detail for its potential to provide early ore feed to support future development.


Holes in the now 22-hole drill campaign, expanded from the initial 18 holes, are laid out on a grid measuring about 2500m-by-1000m in the centre of the main body of the complex and at a spacing of about 500m-by-300m, with the goal of drilling to about 300m.


The program is designed to systematically test the central area surrounding the previous five diamond drillholes to confirm if the shallow mineralisation observed is laterally continuous between the diamond holes and if richer zones of disseminated mineralisation exist.


The first 10 holes have been completed, with each hole taking about two days, while a further 12 holes have been cased to about 60m through the overlying sand and all the remaining pre-collars have been set up. Management adds that the RC drilling technique has been effective through the sand cover, with the target 300m depth reached in all but one of the first 10 holes.


Some holes were continued to deeper than 300m in cases where disseminated mineralisation was noted at the ends of the holes. It includes one hole which, surprisingly for RC, was drilled to a total depth of 522m and terminated in visible sulphide mineralisation. However, assays are yet to be returned.


As the RC drilling assays trickle in, it will be interesting to see if the extensive shallow nickel mineralised area tested has the goods to sustain an open pit, which could perhaps have a back-of-the-envelope plan area of some 9 square kilometres and be up to 200m deep. To be sure of that, the sand cover must be moved. But it is easily excavated, requires little or no drill and blast and could even be moved efficiently with scrapers up a long ramp and then be redistributed later as backfill or rehab.


Time will tell, soon enough.


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