Western Mines Group has unveiled promising nickel sulphide intersections with spot portable X-ray fluorescence (pXRF) readings of up to 24.8 per cent nickel from its seventh diamond drillhole at its 100 per cent-owned Mulga Tank site, some 150km north-east of Kalgoorlie.
It continues to identify the basal contact of the ultramafic intrusive as highly prospective for massive sulphide accumulations similar in style to other operating nickel mines in the area. An additional eight holes of a concurrent shallow reverse-circulation (RC) drilling to an average depth of 300m have been completed as part of an effort to refine the shallow sulphide occurrences.
The work is part of a 5400m RC drilling program at the nickel-copper-platinum group elements (PGE) project on the Minigwal greenstone belt. The company says the intent of the drilling is to systematically test the central area of the intrusive complex to confirm the richness and lateral continuity of the nickel sulphide mineralisation.
The hole (MTD028) certainly met our expectations and the predictability is starting to become something of a feature of Mulga Tank. There are almost no bad holes, with sulphide mineralisation encountered nearly everywhere we drill. Further high-tenor remobilised massive sulphide veinlets were seen at depth, confirming the basal contact of the intrusion is highly prospective for massive sulphides, which continues to confirm our belief this is likely a hybrid Type 1/2 mineral system more akin to Perseverance (nickel mine) - with both disseminated and massive components. Western Mines Group managing director Caedmon Marriott
The Mulga Tank deposit has now been confirmed as a large adcumulate dunite complex of some 15 square kilometres in areal extent, with channel flows extending 12km north-west and containing both type-1 and type-2 classifications of nickel sulphides accumulations.
Type-1 describes stratiform basal massive sulphide deposits, such as the Perseverance nickel mine, and they are characterised by high value per tonne deposits amenable to underground mining. Perseverance has a resource of 50 million tonnes at 2.3 per cent nickel.
Type-2 refers to interstitial disseminated nickel sulphides typified by large open-pit mining to account for the significant tonnage at lower grades of nickel. Mt Keith is an example and has a resource of 643.7 million tonnes going 0.58 per cent nickel. The deposit shows sulphide mineralisation immediately below the 60m to 75m of sand cover, making it amenable to open-cut mining if everything turns up trumps.
Management drilled its latest diamond hole to 1107.5m into footwall basalt-chert-shale and confirmed the presence of four broad zones of nickel sulphide mineralisation of type-1. It was broadly similar to surrounding holes, with several intercepts of high-tenor remobilised massive nickel sulphide veinlets in the lower portion of the hole between 800m to 1000m of type-2.
The spot pXRF reading of 24.8 per cent nickel was logged at 853.2m and was described as immiscible nickel sulphide globules. The sulphides observed throughout the core hole were mostly the nickel-rich minerals pentlandite and pyrrhotite, with visual estimates in concentrations up to 10 per cent.
But Western Mines says caution should be noted, as the values are only a qualitative guide of the mineralisation until laboratory assays become available.
Assays have been returned to the company from its earlier six diamond drillholes, with nickel readings giving up to 2.73 per cent, 0.55 grams per tonne platinum and palladium, 0.08 per cent cobalt and 0.15 per cent copper from various holes and intervals, attesting to the deposit’s rich mineralogic assemblage.
An airborne MagnetoTellurics survey, which is capable of mapping resistivity to a depth of about 1000m, was completed in August and is being processed and integrated with existing datasets to provide a new model of the complex. It should shed further light on the distribution of the sulphide mineralisation.
The key question now remains: could this drilling campaign ultimately put the Mulga Tank deposit in the same world-class realm as the operating Perseverance and Mt Keith nickel mines?
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