Astral Resources NL (ASX:AAR) has returned standout results from the first 17 holes (2,030 metres) of an extensive 99-hole reverse circulation (RC) in-fill drill program at the Theia Deposit within the Mandilla Gold Project in Western Australia.
The region is home to several world-class gold operations, including the Golden Mile Super Pit in Kalgoorlie, operated by Northern Star Resources Ltd (ASX: NST), and the St Ives Gold Mine located south of Kambalda, owned by Gold Fields Ltd. It also hosts the substantial Beta Hunt Gold Mine, operated by Westgold Resources Ltd (ASX: WGX).
Map illustrating the location of the Mandilla, Spargoville and Feysville Gold Projects.
Highlights include:
- 32 metres at 10.78g/t Au from 50m including 3 metres at 99.90g/t Au from 76m, in hole AMRC029;
- 8 metres at 1.11g/t Au from 70m and 2 metres at 95.88g/t Au from 105m including 1 metre at 191.4g/t Au from 105m in hole AMRC023;
- 1 metre at 19.80g/t Au from 45m and 34 metres at 1.56g/t Au from 62m including 1 metre at 20.8g/t Au from 79m in hole AMRC028;
- 3 metres at 2.68g/t Au from 52m and 9 metres at 5.08g/t Au from 62m including 2 metres at 15.8g/t Au from 65 metres in hole AMRC039;
- 1 metre at 10.46g/t Au from 26m, 5 metres at 2.78g/t Au from 47m and 40 metres at 1.07g/t Au from 73m in hole AMRC038;
- 12 metres at 0.87g/t Au from 66m and 16 metres at 2.30g/t Au from 98m including 1 metre at 12.55g/t Au from 113m in hole AMRC027;
- 6 metres at 1.21g/t Au from 45m, 3 metres at 4.48g/t Au from 56m and 17 metres at 2.15g/t Au from 87m including 1 metre at 15.70g/t Au from 87m in hole AMRC036;
- 5 metres at 1.14g/t Au from 66m, 6 metres at 4.41g/t Au from 78m (including 1 metre at 17.66g/t Au from 78m), 12 metres at 1.41g/t Au from 98m and 10 metres at 0.96g/t Au from 114m in hole AMRC025;
- 6 metres at 3.00g/t Au from 48m, 20 metres at 1.37g/t Au from 78m and 13 metres at 0.75g/t Au from 102m in hole AMRC037;
- 2 metres at 3.86g/t Au from 70m and 12 metres at 1.67g/t Au from 99m including 1 metre at 12.31g/t Au from 102m in AMRC033;
- 7 metres at 1.04g/t Au from 66m and 12 metres at 1.61g/t Au from 113m in hole AMRC035;
- 6 metres at 3.21g/t Au from 64m and 6 metres at 1.24g/t Au from 109m in hole AMRC026;
- 16 metres at 0.79g/t Au from 49m, 12 metres at 1.16g/t Au from 91m and 16 metres at 0.97g/t Au from 109m in hole AMRC024; and
- 19 metres at 0.92g/t Au from 45m in hole AMRC030.
Cross-section through Theia illustrating drill trace, assay results and geological interpretation.
“The results of the Theia in-fill program are critical to the successful development of the Mandilla Gold Project,” managing director Marc Ducler said. “Theia represents approximately 75% of the gold production contemplated in the PFS, which highlights the importance of Theia to the overall project economics.
“With that in mind, this first set of results, albeit very early stage, are strongly encouraging. Not only are we seeing the very high-grade intersections, such as 3 metres at 99.9g/t Au and 1 metre at 191.4g/t Au, which are examples of the high-grade gold mineralisation that we would expect at Theia, but we are also seeing good continuity of mineralisation along the length of the hole as per model predictions.
“The three-phase in-fill drilling program is expected to be completed within 8 weeks, by which stage the 3,000-metre diamond drill program targeting high-grade structures within Theia is planned to have commenced. Both of these programs are essential de-risking activities designed to ensure successful project development for Mandilla."
Theia drilling confirms strong grade continuity
The program is targeting an 80-metre-by-120-metre area within the Stage 1 open pit, with 26 holes completed to date and assays returned for the first 17. Astral reports that the results demonstrate strong alignment with the 2025 Mineral Resource Estimate (MRE) of 33.3 million tonnes at 1.1 g/t gold for 1.15 million ounces.
Exceptional results from holes such as AMRC023 and AMRC029 show not only isolated high-grade intercepts but also broad mineralised envelopes, indicating robust continuity. The geology is consistent with prior modelling, with bonanza grades potentially linked to steep high-grade shear zones — a target for upcoming diamond drilling.
The program is being completed in three phases and is expected to wrap up within eight weeks. A 3,000-metre diamond drilling campaign focused on delineating high-grade structures is scheduled to commence shortly thereafter.
Geological setting supports resource expansion
The Theia deposit lies within a shallow-dipping monzonitic granitoid intrusive, hosting wide quartz-veined zones typically 20–50 metres thick. These structures dip gently to the south and are often associated with high vein densities and visible free gold.
The mineralisation model is underpinned by detailed structural logging and petrology studies, with assay trends reinforcing the presence of consistent, predictable mineralisation. Gold is commonly found in quartz veins, with free gold grains up to match-head size observed in multiple drill holes.
The strong performance of this grade-control drilling program is providing further confidence in Astral’s geological model and its resource development strategy at Mandilla.
Exploration ramps up at Spargoville and Feysville
At Spargoville, Astral has commenced a 21-hole, 2,500-metre RC program on behalf of its joint venture with Korea Mine Rehabilitation and Mineral Resources Corporation (KOMIR). The program is testing lithium-pegmatite targets defined by earlier geochemical work, with 4 holes for 482 metres completed so far.
“The KOMIR JV lithium-pegmatite drill program is underway; this is expected to be completed within three weeks. Our preferred engineering partner has been notified, and work is now commencing on contract execution, with notification to the market expected to be made shortly thereafter,” Ducler said.
Meanwhile, once work is complete at Theia and Spargoville, RC drilling will resume at Feysville. Planned activities include a 17-hole (3,000-metre) program at Kamperman and a 30-hole (4,000-metre) regional campaign. A 3,000-metre diamond drill program at Theia is also on track to begin in the December quarter.
These exploration efforts reflect Astral’s strategy to continue de-risking its key assets while progressing toward project development.
Mandilla PFS outlines robust economics
The June 2025 Preliminary Feasibility Study (PFS) confirmed Mandilla’s standalone potential with a proposed seven-pit operation feeding a 2.75-million-tonne-per-annum processing plant. The project is expected to yield 95,000 ounces of gold annually over a 12-year mine life.
The PFS estimates a net present value (NPV8%) of A$1.4 billion using a gold price of A$4,250 per ounce. Theia alone is anticipated to contribute 1.11 million ounces of the 1.48 million-ounce production target, further underscoring its significance within the broader development.
The Mandilla Gold Project comprises the Theia, Iris, Hestia and Eos deposits. All lie within granted mining leases and are not subject to third-party royalties.