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Western Mines ramps up Mulga Tank nickel mission

Updated: Apr 30

Western Mines Group’s RC rig drilling Mulga Tank precollars. Credit: File

Western Mines Group has entered a “new phase” at its Mulga Tank site in Western Australia’s Eastern Goldfields region to test a shallow horizontal zone of disseminated nickel sulphide mineralisation noted in diamond holes under about 60m of sand cover.

The company today confirmed it had kicked off a 5400m reverse-circulation (RC) drilling program with a second rig at the nickel-copper-platinum group elements (PGE) project on the Minigwal greenstone belt, east of Kalgoorlie.

Management says it has progressively defined the campaign’s targets during the past few months in the upper parts of each of five deep diamond drillholes.

It’s great to see us entering a new phase of our exploration at Mulga Tank with the mobilisation of a second rig to the project and the commencement of this RC drilling program. The initial 18 hole program is designed to quickly test a fairly large area across the centre of the main body of the Complex. If the drilling program is successful we hope the results may yield an initial exploration target size for Type 2 Mt Keith-style mineralisation at the project. Western Mines Group managing director Caedmon Marriott

In plan view, the previous diamond hole collars describe an arcuate fence across the centre of the Mulga Tank ultramafic complex.

They were drilled to explore the nickel sulphide potential of the massive dunite body to determine the bottom contact and feeder zone (if any) and the variations within it. The work was also designed to outline the deposit’s shape, which had originally been thought of as lopolithic – that is, like a mushroom.

However, it has turned out to be more of a wedge-shaped chonolith, notably thicker in the east and tapering to thin, shallow subcrop in its western extremities. It has only been laterally defined to date between the end limits of the fence, which shows it to be about 2.3km wide.

Intriguingly, it appears likely from the eastward thickening bottom profile of the chonolith that the full width across the wedge might be at least double that currently inferred through drilling.

During the diamond drilling, Western Mines says it became increasingly apparent that a relatively shallow horizontal zone of disseminated nickel sulphide mineralisation could be defined in the upper portions of the deep diamond holes, starting almost immediately below the base of about 60m to 70m of sand cover and extending down to a vertical depth of about 250m.

A good example is provided by the shallowest mineralisation intercepted in diamond hole “MTD026”, which was between 116m to 246m, with assays showing 130m at 0.31 per cent nickel from 116m, including 13m at 0.35 per cent nickel from 157m.

And it was not long before the creative minds of management considered that the horizontal and partially-weathered, shallow disseminated nickel sulphide mineralisation might be easily mined via open-pit methods, following an easily excavated and relatively low-cost pre-strip of the overlying 70m of sand.

The second RC drill rig, a multipurpose machine, has already been onsite for about a fortnight, establishing pre-collars through the sand cover. It has now begun drilling a grid of holes disposed in an area measuring 2000m-by-1000m across the centre of the main body of the complex, with 500m-by-300m spacing.

It will attempt to drill to a depth of about 300m and is expected to take each hole through the disseminated zone.

Western Mines says the program is intended to systematically test the central area surrounding the RC holes in a bid to confirm lateral continuity of mineralisation between them and to identify any richer zones of disseminated mineralisation. The campaign is expected to be completed in the next two months.

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