Astron Corporation Ltd (ASX:ATR, OTC:ATRNF) has updated the Mineral Resource and Ore Reserve estimates for Mining Licence MIN5532 at its Donald Rare Earth and Mineral Sands Project in Victoria, incorporating detailed rare earth element data for the first time.
The revised estimates confirm Donald Phase 1 as a significant near-term source of heavy rare earths outside China, with improved dysprosium (Dy) and terbium (Tb) production forecasts over the early years of mining.
Updated Mineral Resource – MIN5532
- Total Mineral Resource: 530 million tonnes (Mt) at 4.0% heavy mineral (HM), reported above a 1.0% HM cut-off
- Total rare earth oxide (TREO) grade: 1.4% within the HM fraction
- Heavy rare earth content: 8,500 tonnes of Dy oxide and 1,300 of Tb oxide contained within MIN5532
- Resource includes 400Mt Measured, 110Mt Indicated and 20Mt Inferred material
- Estimate updated using ICP-MS analysis, providing more accurate rare earth oxide (REO) data than previous XRF-based models
MIN5532 represents about 10% of the broader Donald Project area but contains roughly 29% of its total Mineral Resources.
Summary – Revised Mineral Resource at 31 Dec 2025 (2025 MRE)
Grade control drilling strengthens early mine profile
A 2025 grade control (GC) drilling program covering the first 2.5 years of planned mining returned higher grades than the broader resource model:
- ~5% increase in HM grade across the first eight mining blocks
- 6% increase in zircon, 11% increase in monazite and 8% increase in xenotime within the HM fraction
- GC Mineral Resource: 15Mt at 5.2% HM and 1.6% TREO
Astron said the results point to potential grade upside in early-stage production areas, although further work is required to determine whether higher grades extend across the full licence area.
Revised Ore Reserves and production outlook
The updated Mineral Resources have been converted into an Ore Reserve of:
- 293Mt at 4.5% HM and 1.4% TREO, comprising 15Mt Proved (GC area), 240Mt Proved (remaining) and 39Mt Probable
Donald Project MIN5532 Ore Reserves at 31 Dec 2025
At a planned throughput of 7.5Mt per annum (Mtpa), Donald Phase 1 is forecast to:
- Produce 279,000 tonnes of rare earth element concentrate (REEC) over a 39-year mine life
- Deliver ~4,500 tonnes of Dy oxide and ~1,100 tonnes of Tb oxide over life of mine
- Average 144tpa Dy and 22tpa Tb over the first five years — increases of 57% and 22% respectively versus the July 2025 economics study
The updated REEC assemblage reflects a higher proportion of heavy rare earths, which command significant premiums in Western markets following China’s export controls on key heavy rare earth elements.
The Ore Reserve update reflects lower long-term product price forecasts compared with the 2023 Definitive Feasibility Study, though contained Dy and Tb have been disclosed for the first time at 5.4kt and 843t respectively.
The revised estimates were prepared in accordance with the JORC Code (2012), with a parallel technical report released by joint venture partner Energy Fuels Inc under NI 43-101 and S-K 1300 standards.
Donald Phase 1 has received key approvals, with first product shipment targeted for Q1 2028 under the current development schedule.
Location of Astron’s rare earths and mineral sands projects in Victoria