This article is a sponsored feature from Mining.com.au partner Western Mines Group. It is not financial advice. Talk to a registered financial expert before making investment decisions.
Western Australia hosts the largest proportion of the country’s nickel resources with an estimated 90% of its Economic Demonstrated Resources (EDR), followed by Queensland (5%) and New South Wales (4%).
According to Geoscience Australia, Western Australian EDR comprises both sulphide and laterite deposits, while in Queensland it is mostly associated with laterite deposits.
In Western Australia, Western Mines Group (ASX:WMG) has what is now touted as the largest nickel sulphide deposit in the country.
For the past few years the company has demonstrated extensive disseminated mineralisation within the complex – Mount Keith-style nickel mineralisation – at its Mulga Tank Ni-Cu-Co-PGE Project, on the Minigwal Greenstone Belt, in the state’s Eastern Goldfields.
In April 2025, Western Mines completed a first mineral resource estimate (MRE) for the shallow disseminated nickel sulphide mineralisation at Mulga Tank. The deposit is a globally “significant, large-scale, open-pittable” nickel sulphide deposit defined at 0.20% nickel cut-off.
As Mining.com.au reported, Mulga Tank has a resource of 1.968 billion tonnes @ 0.27% nickel, 131 parts per million cobalt, 82ppm copper, and 17 parts per billion platinum and palladium with S:Ni 0.9.
Contained metal in the total resource is 5.3 million tonnes nickel, 257,000 tonnes cobalt, 161,000 tonnes copper, and 1.1 million ounces Pt+Pd.
The resource contains 565 million tonnes at 0.28% nickel, 134 parts per million cobalt, 104ppm copper, and 18ppb Pt+Pd with S:Ni 1.0 in the indicated category. In the inferred category it is 1.403 billion tonnes at 0.27% nickel, 129ppm cobalt, 73ppm copper, 17ppb Pt+Pd with S:Ni 0.9.
Managing Director Caedmon Marriott notes the MRE demonstrates what the company has long stated – “that the main body of the complex hosts a globally significant nickel sulphide deposit, we believe the largest nickel sulphide deposit in Australia and top 10 in the world”.
Recently speaking to this news service, Marriott reckons despite the metal’s inherent value, nickel is a forgotten commodity, adding “there’s essentially no other nickel explorers left”.
Western Mines continues to believe in not only nickel but also its Mulga Tank project.
Visible sulphide mineralisation
Since mid-July 2025, the company has been back drilling and has now completed the first four reverse circulation holes, which are stepout holes outside of the resource.
In early August, a drill rig was converted to diamond drilling and moved up to the Panhandle prospect. The first diamond hole (MTD030) is being drilled with the support of one of Exploration Incentive Scheme grants.
The aforementioned four holes have been drilled for 1,309m all lie within the main body of the Mulga Tank Ultramafic Complex – and importantly, have encountered visible sulphide mineralisation.
As Marriott explains, visible sulphide mineralisation is important, because just seeing the mineralisation in the rock is not necessarily an indication of grade.
“But if you see more sulphide, you’re going to get better nickel results”
“But if you see more sulphide, you’re going to get better nickel results,” he says.
This initial MRE focuses on just the shallow disseminated mineralisation, constrained by the drilling, in what could be a large open pit scenario. Marriott says there are “more than enough tonnes, and it will get bigger still as we extend in a number of directions”.
The focus has become upgrading the resource confidence with further drilling and following up the 23 intersections greater than 1% nickel, including results up to 4.5% nickel and 4.8% copper, clustering in various zones across the complex.
“There’s something big lurking down there from all the indications that we see and so these results are going to start feeding into the labs,” Marriott says.
The Managing Director notes that while nickel is not really on the radars of retail investors, interest in the metal and deposits like Mulga Tank remains among institutional investors and large global players, particularly from Japan.
Mount Keith comparisons
The Mulga Tank Project is located on the Minigwal Greenstone Belt, which lies in the southern Duketon Domain of the Burtville Terrane of the Yilgarn Craton, Western Australia.
The Minigwal Greenstone belt is interpreted from aeromagnetics and historical drilling to consist of two belts of northwesterly trending assemblages of ultramafic, mafic volcanic and sedimentary rocks fault bounded by granite to the east and west.
Within the project area the Archaean bedrock is masked by sand cover of up to 70m. An approximately oval magnetic high feature within tenement has been shown by drilling to be a lopolith shaped dunite intrusion.
Western Mines says the high MgO dunite consists of coarse-grained olivine, displaying predominantly adcumulate to extreme adcumulate texture, with varying degrees of serpentinisation, interstitial magnetite, minor chlorite and sulphides.
In places complete serpentinisation of the dunite has taken place with former olivine cumulate textures pseudomorphically replaced by lizardite. Elsewhere serpentinisation has destroyed primary textural features.
Curvilinear magnetic features emanating from the dunite are interpreted to represent komatiite channel flows. The company says this interpretation of komatiite channels has been confirmed by the first recent regional reverse circulation drilling.
The surrounding footwall of the dunite and komatiite channels consists of basalt and interbedded chert and sulphidic black shales.
Diamond drilling of the dunite intrusion has demonstrated the extensive presence of intercumulus sulphide blebs (predominantly pentlandite), localised at the interstices between former olivine crystals.
This texture is often considered evidence of cotectic olivine-sulphide precipitation and characteristic of Type 2 nickel sulphide systems, exemplified by the Mount Keith deposit.
Drilling has also encountered intersections of thin (more than 20cm) high-tenor massive sulphide veins and immiscible sulphide globules.
The presence of this type of mineralisation in addition to intercumulus sulphide is considered evidence that Mulga Tank represents a so-called hybrid system, in which both cotectic precipitation and gravity settling of sulphides has occurred.
Western Mines says this markedly increases the prospectivity of the system, allowing for possible significant basal accumulations of massive and matrix sulphide.
Nickel uses
A malleable, lustrous, silvery-white metal, nickel has relatively low electrical and thermal conductivity, and strength and toughness at elevated temperatures. It is capable of being magnetised.
One of the most desired attributes of the metal is its anticorrosion properties, with about 80% of nickel used in steel production. When alloyed with other elements, nickel imparts toughness, strength, resistance to corrosion and various electrical, magnetic and heat resistant properties.
The vast majority of global nickel output is consumed in the manufacture of stainless and heat resistant steel.
These steels are used widely in the chemical industry, motor vehicles, medical applications, electronic engineering, and the construction industry. They are also used in consumer products such as sinks, cooking utensils, cutlery and white goods.
There are substitutes for nickel but they are expensive and result in a trade‑off in performance, which compromises the application’s physical or chemical attributes.
Write to Adam Orlando at Mining.com.au
Images: Mining.com.au & Western Mines Group
