Astral Resources NL
Astral Resources Drills 358 Metres of Gold at Theia — And the System Is Still Open at Depth
Astral Resources NL (ASX: AAR) has delivered a standout result from the first hole of its ongoing deep diamond drilling program at the Theia Deposit, part of the 100%-owned Mandilla Gold Project in Western Australia. The Astral Resources Theia gold drill results at Mandilla project centre on drill hole AMRCD263, which intersected 358.23 metres at 1.03 g/t Au from 256.17 metres depth, reaching 614.4 metres downhole — a full 210 metres below the current Mineral Resource Estimate (MRE) boundary.
The mineralisation occurs largely outside the existing resource envelope, pointing to meaningful potential to grow what is already a 1.4 million ounce deposit. With eight holes still to report from the 9-hole, 5,500-metre program, this result sets a compelling tone for what could follow.
When big ASX news breaks, our subscribers know first
What the Numbers Actually Say
The headline intersection of 358.23m at 1.03 g/t Au is notable not just for its width, but for the quality of the higher-grade zones embedded within it. These are not marginal results — several intervals returned spectacular spot grades that reinforce the structural and geological continuity of the Theia system at depth.
| Interval | From (m) | Width (m) | Grade (g/t Au) | Notable High Grades |
|---|---|---|---|---|
| Zone 1 | 285.00 | 9.41m | 1.93 g/t | 0.3m @ 14.6 g/t; 0.3m @ 21.5 g/t |
| Zone 2 | 320.44 | 15.70m | 3.40 g/t | 0.43m @ 121.6 g/t |
| Zone 3 | 352.00 | 127.27m | 1.20 g/t | 0.34m @ 72.2 g/t; 0.59m @ 30.0 g/t; 0.3m @ 71.1 g/t |
| Zone 4 | 515.04 | 81.46m | 1.35 g/t | 1.13m @ 42.7 g/t |
| Zone 5 | 607.75 | 5.75m | 2.00 g/t | — |
The two standout intervals — 127.27m at 1.20 g/t Au and 81.46m at 1.35 g/t Au — occur almost entirely outside the existing resource block model. The implication is direct: these are not just confirmatory results within known mineralisation, they are extensions that have not yet been captured in the current 1.4Moz MRE.
"The first hole from our Theia Deeps diamond drill program delivered highly encouraging results, providing strong evidence that the Theia gold system appears to extend well beyond the limits of the current 1.4Moz Mineral Resource. Geological logging of this hole showed quartz veining, trace sulphides and visible gold — all of which have previously been strong indicators of economic gold mineralisation at Theia."
— Marc Ducler, Managing Director, Astral Resources
Understanding Mineral Resource Extensions — What Does This Mean for Investors?
A Mineral Resource Estimate represents a formal, JORC-compliant calculation of the quantity and grade of mineralisation that has been delineated by drilling and geological modelling to a sufficient level of confidence to be reported publicly. Resources are classified as Measured, Indicated, or Inferred depending on drill density and data quality.
Drilling below the MRE boundary matters because the current estimate represents the three-dimensional envelope of known gold mineralisation at Theia. When new drilling intersects significant grades outside that envelope — particularly below it — it demonstrates the deposit's potential to grow. Furthermore, more tonnes at economic grades can support longer mine life, higher production profiles, and improved project economics.
The Theia Deeps program was specifically designed to probe this question. The 9-hole program was originally designed to test for extensions up to 175 metres below the current MRE floor. However, AMRCD263 has already extended 210 metres below that floor — and the mineralised system remains open.
Key Technical Terms Explained
- g/t Au: Grams of gold per tonne of rock — the standard measure of gold grade
- Downhole depth: The measured distance along the drill hole path from surface
- Diamond drilling (DD): A drilling method using a diamond-tipped drill bit to recover intact core samples for detailed geological analysis
- Visible gold: Gold grains that can be seen in drill core with the naked eye — a qualitative indicator of mineralisation
- Quartz veining: Quartz-filled fractures in rock that commonly host gold mineralisation at Theia
- IGS lithotype: A bleached version of the host monzonite rock at Theia, interpreted as a zone of greater fluid-heat exchange — consistently coincident with ore zones
The Theia Geological Story — Why Does This Deposit Keep Growing?
The Theia Deposit sits within the northern Widgiemooltha greenstone belt, approximately 70 kilometres south of Kalgoorlie, a region with world-class gold credentials including the Golden Mile Super Pit and the St Ives Gold Mine.
Gold mineralisation at Theia is structurally controlled — hosted within quartz vein arrays and hydrothermal alteration along the western margin of the Emu Rocks Granite. The mineralised footprint extends over a strike length of more than 1.6 kilometres, with a second sub-parallel structure at the nearby Iris Deposit adding another 700 metres of strike, bringing the combined mineralised zone to more than 2.3 kilometres.
The Astral Resources Theia gold drill results at Mandilla project are particularly significant because the consistency between observable geological features and confirmed gold assays was clearly demonstrated. Quartz vein density and visible gold occurrences in the drill core correlated strongly with economic grade zones.
How Reliable Are the Geological Indicators?
According to the report, 75% of visible gold occurrences returned a gold grade above the Theia MRE grade, and 93% returned a grade above the MRE lower cut-off. This correlation provides geological confidence that the positive logging observations in subsequent holes are meaningful indicators of further mineralisation.
In addition, the geological logging of the third completed hole (AMRCD264) was compelling enough to prompt an extension of that hole beyond its original planned depth of 500 metres to a final depth of 605.3 metres — a telling signal from the on-site geology team about what they were observing in the core.
The Broader Picture — Mandilla's Scale and Stage of Development
The Theia deep extension drilling is taking place against a backdrop of significant project advancement at Mandilla. The project has progressed beyond early grassroots exploration — it has a completed Pre-Feasibility Study, a maiden Ore Reserve, and an active infill drilling program to support the commencement of mining.
Group Mineral Resource Summary (JORC 2012)
| Project | Tonnes (Mt) | Grade (g/t Au) | Contained Gold (oz) |
|---|---|---|---|
| Mandilla | 53.5 | 1.0 | 1,736,000 |
| Feysville | 5.0 | 1.2 | 196,000 |
| Spargoville | 3.0 | 1.4 | 139,000 |
| Total | 61.6 | 1.0 | 2,072,000 |
Group Ore Reserve Summary (JORC 2012)
| Project | Tonnes (Mt) | Grade (g/t Au) | Contained Gold (oz) |
|---|---|---|---|
| Mandilla | 34.3 | 0.9 | 1,000,000 |
| Feysville | 2.3 | 1.2 | 88,000 |
| Total | 36.6 | 0.9 | 1,082,000 |
The Mandilla Pre-Feasibility Study, completed in June 2025, outlined a standalone project comprising seven open pit mines feeding a 2.75 million tonne per annum processing facility, producing approximately 95,000 ounces of gold per year for the first 12 years.
At a base case gold price of A$4,250/oz, the PFS returned an NPV (8% discount rate) of $1.4 billion. Consequently, at A$6,250/oz, that NPV increases significantly to $2.9 billion.
Metallurgical testing across all Mandilla deposits — Theia, Iris, Eos and Hestia — has demonstrated high gravity recoverable gold, fast leach kinetics, and strong overall recoveries with low reagent consumption and coarse grinding, all of which support the processing economics underpinning the PFS.
What Comes Next — Near-Term Catalysts
The drilling program is reported to be active and moving quickly. Three of nine holes are now complete, and results are flowing through the assay pipeline.
Immediate pipeline:
- AMRCD259 (hole 2) — processing complete, assay results pending
- AMRCD264 (hole 3) — processed, samples dispatched to laboratory
- AMRCD265 (hole 4) — currently being drilled
Parallel workstreams also underway at Mandilla:
- A reverse circulation (RC) rig is continuing infill drilling on the Stage 1 Theia open pit, targeting 12.5m x 12.5m drill density to support an increase in Measured Resources ahead of mining commencement. Approximately 6,000 metres of the first phase (23,000 metres) of a three-phase program have been completed.
- Sterilisation drilling is continuing pending heritage clearance surveys.
- RC and diamond drilling is being planned for the Kamperman deposit at Feysville, with heritage clearance surveys commenced in April.
The combination of assay results from holes 2 and 3 — both of which have already been processed — means further news flow from the deep drilling program is reported to be imminent.
The Investment Case — Why Does This Result Matter?
The Theia Deeps program is addressing a fundamental question about the scale of one of Western Australia's more advanced development-stage gold projects: how much bigger can it get?
The first hole has provided a compelling early answer. The Astral Resources Theia gold drill results at Mandilla project confirm the intersection of continuous, wide gold mineralisation extending 210 metres below the current MRE, with multiple zones above 1 g/t Au over widths exceeding 80 and 127 metres, demonstrating that the Theia system may not be bottoming out.
Several factors, however, make this result particularly significant for the investment case:
- Resource growth optionality at reduced discovery risk. The Theia Deposit is already established. Depth extensions represent potential upside from a known, structurally understood system rather than greenfield exploration.
- Project economics are already robust without the extensions. The PFS NPV of $1.4 billion at A$4,250/oz — rising to $2.9 billion at A$6,250/oz — is based on the existing resource base. Successful depth extension has the potential to further enhance mine life and production profile.
- Two rigs operating simultaneously. Both the deep diamond program and the Stage 1 infill RC program are running concurrently, meaning the company is advancing project de-risking and resource growth in parallel.
- Geological confidence appears high. The correlation between visible gold, quartz vein density, and assay results in AMRCD263 is reported to be strong — and the same indicators are being observed in the geological logging of subsequent holes.
- Eight holes still to report. The full 9-hole program is less than one-third of the way through its assay reporting cycle. The potential for additional high-impact results is substantial.
The next major ASX story will hit our subscribers first
Why Investors Should Watch Astral Resources Closely
Astral Resources occupies a specific position in the Australian gold development space: a project that has moved beyond early-stage exploration to have a completed PFS, a maiden Ore Reserve exceeding one million ounces, and now active drilling evidence that its cornerstone deposit may be materially larger than currently estimated.
The Theia Deeps program represents a systematic, drill-tested investigation of a mineralised system that has already demonstrated strong geological continuity over more than 1.6 kilometres of strike. Furthermore, the first hole suggests depth may not be a constraint.
With assay results from holes 2 and 3 pending, drilling on hole 4 underway, and infill RC drilling advancing toward mining commencement at Stage 1, Astral Resources enters a period of dense news flow with multiple catalysts converging simultaneously.
"Astral Resources (ASX: AAR) has confirmed that the Theia gold system extends well beyond its current 1.4 million ounce MRE, with the first hole of a 9-hole deep diamond program intersecting 358 metres of gold mineralisation — 210 metres below the existing resource boundary. Against the backdrop of a completed PFS demonstrating a $1.4 billion NPV and over 2 million group ounces of resources, the Astral Resources Theia gold drill results at Mandilla project represent a well-funded test of significant deposit growth potential. With eight holes remaining and results from holes 2 and 3 imminent, investors have multiple near-term catalysts to monitor."
Ready to Dig Deeper Into Astral Resources' Mandilla Gold Project?
With 358 metres of gold intersected below the current resource boundary, a completed Pre-Feasibility Study returning an NPV of $1.4 billion, and eight holes still to report, Astral Resources (ASX: AAR) is entering one of its most catalyst-rich periods to date. For investors seeking exposure to a development-stage Australian gold project with genuine resource growth potential, now is the time to get across the full story. Visit astralresources.com.au to explore the Mandilla Gold Project, review the company's latest announcements, and assess the investment case for yourself.
