Western Mines Group Confirms Nickel Zone Uplifted to Near Surface at Mulga Tank
Key Takeaways
- All six western margin holes confirmed the five-part basal sequence geochemical stratigraphy, validating WMG's geological uplift thesis and opening a materially larger prospective footprint at Mulga Tank.
- MTRC001 returned a cumulative 442m at 0.26% Ni with an S:Ni ratio of 1.4, including a higher-grade basal zone of 74m at 0.32% Ni from 762m and 23m at 0.42% Ni from 812m.
- MTRC084 intersected a near-surface zone of 13m at 0.41% Ni with 0.21g/t Pt+Pd from just 98m depth, while MTRC083 ended in mineralisation at 0.47% Ni — the highest grade in the dataset — leaving the zone open for follow-up.
- A WA Government co-funded seismic survey covering approximately 35km² of the Complex, with the grant increased to $300,000, is scheduled for October 2026 to image basal contact geometry and direct future drilling.
- WMG holds the largest nickel sulphide deposit in Australia at 1,968Mt containing over 5.3Mt of nickel, against a current market capitalisation of just $20.21 million.
Western margin drilling confirms basal target zone at Mulga Tank
New assay results from the diamond tail of hole MTRC001 and RC holes MTRC083 to MTRC087 have confirmed that the basal sequence of the Mulga Tank Complex is uplifted into the western margin, validating a key geological thesis for Western Mines Group (ASX: WMG).
The headline result from MTRC001 — combining prior RC samples with the new diamond tail assays — is a cumulative 442m at 0.26% Ni, 129ppm Co, 78ppm Cu, and 27ppb Pt+Pd with an S:Ni ratio of 1.4. Within that interval, a higher-grade basal zone returned 74m at 0.32% Ni, 142ppm Co, 115ppm Cu, and 31ppb Pt+Pd from 762m, including 23m at 0.42% Ni from 812m.
All six holes sit on the western and southwestern margin of the Complex, a new area being tested for near-surface basal mineralisation. These are not routine infill results — they confirm a geological model that opens up a materially larger prospective footprint.
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Drill results — holes MTRC001 and MTRC083–MTRC087
Each of the six holes displays the now-familiar geochemical stratigraphy of the basal sequence: broad mineralised horizons rich in Ni, S, Cu, and PGEs, separated by barren dunite intervals lacking those chalcophile elements. The cumulative results across the programme are presented below.
| Hole ID | Cumulative Interval | Ni% | Co (ppm) | S:Ni |
|---|---|---|---|---|
| MTRC001 | 442m | 0.26% | 129 | 1.4 |
| MTRC083 | 171m | 0.30% | 134 | 0.8* |
| MTRC084 | 79m | 0.29% | 113 | 0.5 |
| MTRC085 | 169m | 0.26% | 125 | 1.2 |
| MTRC086 | 124m | 0.29% | 115 | 0.5* |
| MTRC087 | 98m | 0.21% | 117 | 1.9* |
*Ending in mineralisation
Two standout results within this dataset are worth calling out specifically:
- MTRC084 shallow zone: 24m at 0.35% Ni, including 13m at 0.41% Ni, 177ppm Cu, and 0.21g/t Pt+Pd from 98m — a robustly mineralised interval near surface, below the sand cover, that preliminary modelling interprets as an enriched zone of the middle mineralised horizon of the basal sequence.
- MTRC083 final interval: 8m at 0.47% Ni from 310m, with the hole ending in mineralisation. Preliminary interpretation suggests following up in a WSW direction may intersect the zone at shallower depth.
Managing Director Caedmon Marriott
“…MTRC084 showed a robustly mineralised shallow zone of +0.4% Ni close to surface, whilst MTRC083 appeared to be entering a high nickel zone towards the end of the hole.”
What is the basal zone of an ultramafic complex — and why does it matter?
Understanding what WMG is targeting requires a brief look at how magmatic nickel deposits form.
When an ultramafic magma body (a very high-temperature, magnesium-rich igneous intrusion) cools and crystallises, dense, nickel-bearing sulphide liquids tend to sink through the melt and pool at the base of the body. This accumulation zone — the basal contact — is where the richest nickel sulphide mineralisation tends to concentrate. Globally significant deposits, such as the Perseverance mine in Western Australia, formed through exactly this process.
The five-part geochemical signature WMG uses to identify this sequence is:
The pattern of broad nickel sulphide mineralisation across Mulga Tank has been consistent across multiple drill phases, with the five-part geochemical stratigraphy appearing repeatedly as the programme has stepped out across different parts of the Complex.
- A mineralised zone with elevated Ni, S, Cu, and platinum-group elements (PGEs — specifically platinum and palladium)
- A barren dunite interval, a rock type lacking S and chalcophile elements (elements with a chemical affinity for sulphide)
- A second mineralised zone
- A second barren dunite interval lacking S and chalcophile elements
- A third mineralised zone representing the active basal contact
In a typical ultramafic complex, this basal sequence sits at great depth — over 870m in the central portions of the Mulga Tank Complex. WMG’s thesis is that the southwestern margin has been geologically uplifted, bringing that same basal sequence much closer to surface. MTRC001’s entire ~790m dunite package is interpreted as the complete basal sequence, with the dolerite marker horizon (a distinctive rock layer used as a stratigraphic reference) appearing in the top few metres of the hole.
The S:Ni ratio (sulphur-to-nickel ratio) is a useful investor-facing indicator here. When this ratio exceeds 0.5, it signals that nickel is being hosted within sulphide minerals rather than trapped inside olivine crystals. Sulphide-hosted nickel is potentially recoverable through conventional processing. Olivine-trapped nickel is not. All six holes returned intervals with S:Ni above this threshold.
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Vectoring to richer zones — what happens next
The strategic significance of these results extends beyond the individual intercepts. WMG notes in the announcement that potential zones of richer mineralisation may not occur in the same location across both mineralised horizons within the Complex — a characteristic that effectively doubles the prospective area.
Two independent mineralised horizons, each traceable across several hundreds of metres to kilometres, each potentially hosting richer zones at different lateral positions. Modelling the architecture of how those horizons behave across the southwestern margin is how WMG intends to direct future drilling.
Two follow-up targets have been identified:
- MTRC084 middle horizon: Follow-up drilling to the NNE may find broader near-surface intervals within the enriched middle mineralised horizon.
- MTRC083 western zone: Follow-up in a WSW direction may intersect the elevated nickel zone at shallower depth.
Managing Director Caedmon Marriott
“…Modelling of the architecture of the Complex in this southwestern area, combined with assay results, may help vector towards richer zones.”
Supporting this work is WMG’s active seismic survey, co-funded by the WA State Government’s Exploration Incentive Scheme (EIS). The original grant of $250,000 has been increased by an additional $50,000 to $300,000 by the EIS programme. The survey will cover approximately 35km² of the Mulga Tank Ultramafic Complex and is designed to image the architecture of the body, particularly the geometry of the basal contact at depth. The Programme of Work (PoW) for site preparation has already been granted. The seismic contractor is expected to mobilise to site at the end of September 2026, with the survey anticipated to be undertaken in the first two to three weeks of October 2026.
Company snapshot
- ASX: WMG | Share price: $0.155 | Market cap: $20.21m | Cash: $1.58m (30 June 2026)
- Shares on issue: 130.37m
- Mulga Tank Mineral Resource: 1,968Mt at 0.27% Ni, over 5.3Mt of contained nickel, announced April 2025 as the largest nickel sulphide deposit in Australia
- Flagship project: Mulga Tank Ni-Co-Cu-PGE Project, Minigwal Greenstone Belt, Eastern Goldfields WA (100% WMG)
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