Tungsten Mining NL (ASX: TGN) told the market on 11 August 2026 that reverse circulation and diamond drilling had started at its Watershed tungsten project in Far North Queensland. The programs are not exploration. Both are aimed at the ground the company intends to mine first, and both exist to feed a mine plan that already has a study, an approvals package and a target date attached to it.
The reverse circulation program comprises 175 holes for about 15,000 metres and is expected to take around four months. The north-south holes tighten drill spacing to a 20 m by 20 m pattern across known high-grade mineralisation in the planned initial mining areas, with the stated purpose of raising confidence in the continuity, geometry and grade distribution of that material. The diamond program is 75 holes for about 5,700 metres over roughly three months, collecting metallurgical and geotechnical samples for process design, pit design and detailed engineering, with the core also logged and assayed. Both feed an updated resource model. Initial results are expected from October 2026.
The study the drilling supports
Watershed sits about 130 km north of Cairns on granted mining leases with an existing Environmental Authority for open-pit development. Vital Metals completed a definitive feasibility study on it in 2014, and Tungsten Mining acquired the project in August 2018.
On 18 June 2026 the company published an updated resource and a Preliminary Economic Evaluation on the same day. The resource was restated at a 0.04 per cent tungsten trioxide cut-off, reduced from 0.05 per cent, which Tungsten Mining attributed to stronger global tungsten prices making lower-grade material economic. On that basis Watershed reports 69.7 Mt at 0.109 per cent tungsten trioxide for 76,000 tonnes of contained metal, comprising 12.5 Mt at 0.126 per cent Measured, 41.9 Mt at 0.104 per cent Indicated and 15.3 Mt at 0.112 per cent Inferred. The company said contained metal rose 8 per cent against the prior estimate, which the corporate website still records as 49.3 Mt at 0.14 per cent tungsten trioxide at the older cut-off.
The evaluation put pre-tax net present value at A$1,309M at an 8 per cent discount rate with a pre-tax internal rate of return of 198 per cent and a nine-month payback from first ore. Pre-production capital was estimated at A$274M within a range of plus or minus 25 per cent, with a life-of-mine operating margin of 56 per cent, a strip ratio of 1.3 and an eight-year mine life. The flowsheet is conventional ore sorting, gravity and flotation in a mobile and modular plant configuration.
Funding and timetable
Tungsten Mining is targeting a final investment decision in September 2026 and first production in the first half of 2027. On 24 August it appointed Cutfield Freeman & Co as debt adviser, a firm the company says has completed more than US$25 billion of mining finance transactions across 60 countries. Chairman Gary Lyons said the objective is not simply to secure debt but to establish the optimum capital structure, with debt assessed alongside strategic investment, offtake-linked funding and government support. An Indigenous Land Use Agreement is in place alongside the mining leases and environmental approval.
Analysis: what a 20 by 20 metre pattern is actually buying
Drilling on a 20 m by 20 m grid is expensive per tonne and only makes sense in a narrow set of circumstances. It is the spacing used when a company intends to dig a specific volume of rock within a defined period and needs the block model to be reliable at the scale of an individual mining bench, not at the scale of a deposit. That the program is described as covering areas targeted for initial mining, rather than the resource as a whole, is the informative detail: this is grade control work being done ahead of a decision rather than after it.
The reason it matters at Watershed is the grade. At 0.109 per cent tungsten trioxide, the deposit contains roughly one kilogram of contained metal per tonne of rock. At that tenor, small errors in local grade estimation translate into large proportional errors in metal delivered to the plant, and the economics of the study depend on early years performing. A nine-month payback is only achievable if the first ore mined is the high-grade material the plan assumes it is. The RC program is the test of that assumption, and it will report from October, ahead of a final investment decision the company has targeted for September.
The cut-off change bears on the same point. Lowering the reporting cut-off from 0.05 per cent to 0.04 per cent raised tonnes and contained metal while lowering average grade, and the company was explicit that price, not new drilling, drove the revision. That is a defensible reporting choice, but it makes the resource a function of the tungsten market as much as of the geology, and a resource sized at one price behaves differently if that price retreats. The 198 per cent internal rate of return in the evaluation carries the same sensitivity, and a Preliminary Economic Evaluation is not a feasibility study.
The market context is genuinely tight, which is why the company can make these arguments at all. USGS records no commercial tungsten mining in the United States since 2015, net import reliance above 50 per cent of apparent consumption in each year from 2020 to 2024, and China supplying 27 per cent of US imports of ores, concentrates and other forms between 2020 and 2023. About 60 per cent of American tungsten consumption goes into cemented carbide parts for cutting and wear-resistant applications. A new open-pit source outside China is scarce, which shapes both offtake discussions and the government funding initiatives Tungsten Mining says it is pursuing.
Three things would show whether the schedule holds. Whether the October assays confirm the high-grade continuity assumed in the initial mining areas. Whether the metallurgical samples from the diamond program support the ore sorting, gravity and flotation flowsheet at the design recoveries, given ore sorting is doing considerable work at this grade. And whether debt terms are agreed in time to make a September final investment decision meaningful, since Cutfield Freeman was appointed only weeks before that target.
What the company says happens next
Secondary approvals are progressing to allow site works, early works including civil works for the access road and laydown areas were expected to begin in June 2026, and detailed civil engineering has started with a front-end engineering and design phase for facilities from July 2026. The company has flagged an initial preliminary investment decision to allow procurement of long-lead items ahead of the final decision. It says it will update the market on drilling activities and assay results as they arrive.
