Terrain Minerals has confirmed a potential high-grade, district-scale tungsten system at its 100 per cent owned Smokebush project in WA's Mid West region.
A rigorous review of historical drilling - originally aimed at gold and silver - has uncovered impressive grades for the highly sought-after critical metal, effectively revealing a whole new exploration play which has been hiding in plain sight.
Re-assaying of previously assay-capped drill samples from the project, 350 kilometres north of Perth, has returned a headline hit of one metre at 0.75 per cent tungsten trioxide from 144m at the company's Lightning prospect, in the northern extremity of the project area.
The re-analysis campaign has so far identified 20 drill intercepts grading more than 1000 parts per million (ppm) tungsten from 16 holes across five separate prospects.
The discovery came after a review of the company’s drill hole database identified 13 samples, which had previously returned tungsten results at exactly 2000ppm, the established cap imposed as an upper instrumental detection limit for the standard assay method used at the time.
With the true grades unknown, Terrain sent the old assay pulps back to the lab for sodium peroxide fusion analysis, a technique featuring a complete digest without the previous reporting ceiling.
The hunch paid off handsomely, with 11 of the 13 samples returning grades that shattered the previous 2000ppm analytical ceiling. The best result from the re-assaying campaign was 1m hit grading 0.75 per cent tungsten trioxide, equivalent to 5962ppm tungsten.
Other significant results include 2m at 0.55 per cent tungsten trioxide from 137m, within a broader seven-metre zone grading 0.19 per cent tungsten trioxide. Additional high-grade hits came in with 1m at 0.47 per cent tungsten trioxide from a shallow 26m, 1m at 0.41 per cent from 88m and another shallow hit of 1m at 0.47 per cent tungsten trioxide from just 26m.
Notably, deeper downhole intercepts, including 1m assaying 0.41 per cent tungsten trioxide from 356 m, confirm that the mineralised system has vertical continuity and remains open at depth.
To place these results into perspective, the average background abundance of tungsten in the earth's granitic crustal rocks is a mere 1.5 to 2.5ppm, equivalent to 0.00015 and 0.00025 per cent.
Terrain’s individual one-metre intercepts exceeding 0.40 per cent tungsten trioxide represent an intense concentration of metals that comfortably stacks up against active established Australian production benchmarks.
For instance, EQ Resources’ Mt Carbine mine in Queensland operates a globally significant, bulk-tonnage sheeted quartz-vein system with a global resource grade of 0.23 per cent tungsten trioxide. Terrain’s broader intercept of 7m going 0.19 per cent tungsten trioxide demonstrates the potential for the project to host comparable bulk-mineable widths.
Intriguingly, Terrain's top-tier hits of 0.75 per cent and 0.55 per cent tungsten trioxide approach the premium grades seen at Group 6 Metals' Dolphin mine on King Island, widely regarded as one of the world's highest-grade tungsten skarn deposits outside China. Remarkably, Dolphin's own underground reserves average 1.24 per cent tungsten trioxide.
The company says the tungsten mineralisation has been identified over an area estimated at 6km by 5km, with its absolute lateral and depth limits remaining undefined. Importantly, only about one-third of the entire Smokebush drill sample database has ever been assayed for tungsten, suggesting the full extent of the system could be manifestly understated.
Geological analysis indicates a highly evolved magmatic-hydrothermal system where fluids have reacted along the margins of neighbouring greenstone terrain. The tungsten occurs in two chemically distinct expressions across the project.
At the company's Lightning and Hurley prospects, the mineralisation carries negligible bismuth, pointing to a classic scheelite system formed where fluids migrated into calcium-rich mafic rocks typically formed some distance from a granite source.
In contrast, at its Cota and T16 prospects, the tungsten is accompanied by elevated bismuth and molybdenum, highlighting a zone likely much closer to the primary granitic intrusion that supplied the mineralising fluids.
This spatial distribution across multiple unrelated prospects indicates a genuine district-scale mineralising event rather than just an isolated pocket. The discovery adds a potentially significant new string to the bow of a project already noted for its gold and silver endowment.
In July, Terrain tabled a maiden inferred mineral resource for the Lightning deposit at Smokebush of 677,000 tonnes at 2.5 grams per tonne gold for 54,000 ounces, in addition to 156,500 ounces of silver.
Tungsten is listed as a critical mineral by Australia, the United States and the European Union, prized for its hardness, exceptionally high melting point and high density. Its main use is in tungsten carbide for drill bits and cutting tools, with growing demand also coming from the aerospace, defence and semiconductor industries.
China currently dominates the global market, supplying more than 80 per cent of mined tungsten. Reflecting increasing geopolitical supply pressures and tight export licensing, the European price for ammonium paratungstate (APT) surged from US$475 (A$685) per metric tonne unit (mtu) - where one mtu equates to 10 kilograms bulk weight of contained tungsten trioxide - in mid-2025 to US$3,075 (A$4432) per mtu by late July 2026.
Terrain Minerals executive director Justin Virgin said: “The Mt Mulgine region has long been recognised for its gold and tungsten potential, with projects targeting both commodities progressing towards development just a stone’s throw from our Lightning Project. Importantly, before drilling a single hole at Smokebush specifically for tungsten, we had already returned grades above 0.4% WO₃ in five separate holes. Given these results, we are adding up to 12 holes to our upcoming drilling program, designed primarily to test for further tungsten mineralisation.”
The company says it will add up to 12 reverse circulation holes to its upcoming Smokebush drilling program to directly test the tungsten potential at the Lightning, Hurley, Cota and T16 targets, with a current plan to drill three holes into each of the four prospects. Final collar locations, drill orientations and depths are still to be confirmed.
In parallel, Terrain plans to audit its other stored drill pulps to determine how many more untested historical samples can be re-assayed. That is the easiest and cheapest new sample acquisition you can get. For an explorer, there are few things more satisfying than finding something valuable hiding in plain sight within your own data.
By simply taking a second look at samples originally drilled for gold, Terrain has potentially opened up a whole new critical minerals play at Smokebush. With two-thirds of its historical drill samples yet to be tested for tungsten and a dedicated drilling program now on the cards, the company looks well placed to find out how extensive this tungsten system might be.
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