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Western Mines eyes 2 billion tonnes for Mulga Tank nickel

Updated: Apr 30

Western Mines Group has estimated some huge numbers for its Mulga Tank nickel project. Credit: File

Western Mines Group has estimated that potential exists for a globally-significant 350 million to 2.2 billion tonnes grading between 0.24 and 0.35 per cent nickel in its Mulga Tank project near Kalgoorlie in Western Australia.

The company’s maiden JORC exploration target estimate applies specifically to its modelling of an extensive, shallow and potentially open-pittable body of disseminated nickel sulphide mineralisation lying within the main body of the ultramafic complex.

The model estimates that potential mineralisation within the zone also includes 120 to 150 parts per million cobalt, with a sulphur-to-nickel ratio in the range of 1.1:1.3. The recent modelling took account of all the company’s relevant drilling results at its Mulga Tank complex and has been reviewed by independent consultants CSA Global.

This is a significant milestone for both the project and the Company. Results from Mulga Tank have been building over the last 12 months and this Exploration Target marks a culmination of the work and demonstrates the potential for the Complex to host a globally significant nickel sulphide deposit, perhaps several million tonnes of contained nickel, possibly the largest nickel sulphide deposit in Australia and among the top 10 globally. Western Mines Group managing director Dr Caedmon Marriott

Marriott also said modelling highlighted a higher-grade core to the mineralisation and pointed out that this year’s exploration work had begun with an initial reverse-circulation (RC) program of mainly infill drilling. It will be followed by a deep diamond hole and then further RC drilling to target extensions of the exploration target zone.

The shallow disseminated mineralisation is a distinct and remarkably uniform and continuous zone that became apparent in early diamond drilling aimed at fleshing out the overall dimensions, shape and depth limits of the nickeliferous dunite body that lies at the heart of the complex, while also testing its potential for massive nickel sulphides.

The company established a new 22-hole RC drilling program on a 500m-by-300m grid pattern to investigate the new zone and establish its thickness, grade consistency and lateral extents. The campaign had a phenomenal hit rate, with just a single hole falling short in expectations.

The disseminated zone starts just below the original surface level, which is covered by recent sand to depths of about 70m. About 20m of oxidised, upper disseminated mineralisation has not been included in the exploration target estimate, the upper limit of which has been established for modelling purposes at 90m depth.

The lower limit of the exploration target estimate has been set at 370m below surface level, which is the average depth of the RC drilling to date, yielding a nominal maximum thickness of the disseminated zone of 280m.

The lateral limits of the exploration target estimate are defined by a rectangular area measuring 3.5km east-west by 1.9km north-south, which encloses all 22 holes of the RC drilling program and includes 10 diamond drill holes.

The estimate highlights the massive overall potential for the company’s long-overlooked and remarkable Mulga Tank project that lies within a world-renowned nickel province. The project’s famed nickel resource neighbours include Kambalda Nickel Operations with its 35 million tonnes at 3.1 per cent nickel, the Perseverance Mine with its 50 million tonnes running 2.3 per cent nickel and the Mt Keith Mine with its 643.7 million tonnes going 0.58 per cent nickel.

Further encouragement for the strong potential for the likely growth of the overall resource scale of the Mulga Tank mineralisation comes from the database beyond that used in the current exploration target estimate.

Western Mines has also put in 17 diamond drillholes for a total of 11,712.8m, analysed 15,115 drill samples and undertaken 20,525 portable x-ray diffraction analyses on diamond drill core. It has also undertaken several geophysical surveys including down-hole electromagnetics (DHEM), moving loop electromagnetics (MLEM), ground-based gravity surveying and airborne MobileMT (magneto-telluric) surveys.

Other historical data has also been reviewed, including 12 diamond core holes for a total of 4399.4m. The company says the information contained in the holes has been used in the overall assessment of the complex, but has not been included in any geochemical resource modelling.

Importantly, all the data put together shows that potential exists at Mulga Tank for three styles of possible nickel mineralisation – the disseminated Mt. Keith style, the Perseverance style and the Kambalda style. The company has secured all the identification it needs for the first style, but still needs to extend it to its limits in a program that has already begun.

Geophysics has identified elements of the second style, a basal form of massive nickel sulphide mineralisation and the company is planning a third deep diamond hole to test for possible intersections of “cloud” sulphide, which might lead to the identification of a sulphide-enriched keel or feeder vent potential.

Finally, belt-wide drilling is required to evaluate the potential for high-grade channel mineralisation that could be more than 15km long.

The company has already kicked off a further 37 RC holes to infill and expand current mineralisation, with the first 17 holes mainly targeting the higher-grade core identified in the disseminated by initial modelling.

In all, Western Mines looks well on the way to identifying a remarkable triad of nickel resource possibilities all bundled up in one project. If it can pull off an open-pittable, near-surface disseminated deposit at the outset, which could sustain an economic operation on its own, it may be able to continue to develop its deeper and possible multiple branches of massive sulphide potential that is mostly at greater depths.

The upcoming deep diamond hole may help answer part of that question.

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