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Iron ore drilling reveals nickel sulphides for Macarthur

Updated: May 20

Drilling for Macarthur Minerals in WA’s Central Goldfields. Credit: File

Macarthur Minerals has identified the potential for a significant komatiite-hosted nickel sulphide mineralised system at its wholly-owned Lake Giles project, 150km north-west of Kalgoorlie in Western Australia’s Goldfields region.

The company has a significant database of drilling results from iron ore exploration and a review has revealed 319 holes with results greater than 0.1 per cent nickel, including 150 holes with more than 0.2 per cent nickel. The best readings include 11.5m at 1.03 per cent nickel from 10.5m and 2.01 per cent nickel in rock chips.

The fact that half of the historical drilling has not yet been analysed for nickel provides the possibility for further targets to emerge when assaying is complete.

Macarthur said the geological unit with potential for nickel at Lake Giles is a komatiite ultramafic with similarities to the Lake Johnston komatiite system that hosts the rich Maggies Hays deposit with a resource of 12.3 million tonnes at 1.5 per cent nickel before mining. The nearby Emily Ann deposit had a pre-mining resource of 1.5 million tonnes at 3.5 per cent nickel.

Significant historical drilling and trench sampling intercepts featured 150 drill holes with intercepts greater than 0.2 per cent nickel, including 128m at 0.17 per cent nickel from 108m, 106m grading 0.15 per cent and a 23.5m hit going 0.85 per cent nickel, which housed 11.5m at 1.03 per cent nickel from 10.5m. Rock chips from gossan outcrop have yielded up to 2.61 per cent cobalt and 2.01 per cent nickel.

Macarthur has identified seven advanced, but untested, targets considered highly-prospective for nickel mineralisation. Further review of historical exploration data, including geology, geophysical and geochemical survey, is likely to define more promising nickel targets and management believes it will lead to the definition of nickel mineralisation at Lakes Giles.

The company completed 41 diamond drill holes at its Moonshine and Moonshine North targets in 2019 and the work intersected altered komatiites that are yet to be assayed for nickel.

Macarthur plans to conduct nickel-specific targeted exploration, including assaying selected diamond core and RC drill chips for nickel and a broad spectrum of elements. Downhole electromagnetic surveying will be conducted on targeted open holes, as well as further ground-based electromagnetic surveying upon recommendation from geophysics company, Newexco.

Yerilgee Greenstone projects remain the only untested Greenstone belt in the Yilgarn Craton for nickel sulphides. There were a few pleasant surprises with broad intercepts of altered komatiites that appear prospective for nickel noted within the geotechnical diamond drilling in Moonshine as part of our magnetite feasibility study that we are excited to get analysed with a nickel focus. Macarthur Minerals chairman Cameron McCall

Managament is seeking potential partners to accelerate a nickel discovery within the Lake Giles project that is surrounded by Dreadnought Resources’ Central Yilgarn operation, which is being actively explored for nickel and gold.

Lake Giles is an advanced iron ore project with a completed feasibility study to use conventional open-pit mining methods for a series of banded iron formation, hematite and magnetite prospects. Macarthur’s Lake Giles tenements cover the Yerilgee greenstone belt in the central part of the Southern Cross Province of the Yilgarn Archaean Craton.

Geoscience Australia’s 2016 report on the “Potential for intrusion-hosted Ni-Cu-PGE sulphide deposits” highlighted the prospectivity as moderate to high for either or both tholeiitic intrusion-hosted and komatiite-hosted deposits within the Yerilgee greenstone belt. Macarthur says available historical data indicates there is potential for nickel sulphide and gold mineralisation within the extensive ultramafic rock package.

Having taken over Lake Giles in 2005 with the express purpose of searching for nickel, before moving all of the company’s focus to iron ore the following year, Macarthur may soon celebrate a switch hit back to its original quest.

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