Astral Resources Hits 33m at 5.02g/t Gold Below Theia Pit, Eyeing Underground
Key Takeaways
- Hole AMRCD377 delivered 33m at 5.02g/t Au from 450m and 23m at 2.39g/t Au from 418m, both beneath the April 2026 Theia pit shell.
- It sits 60 metres from AMRCD378, which returned 52.75m at 4.67g/t Au, so two holes on one section now show wide, high-grade gold below the shell.
- Holes AMRCD466 and AMRCD467 confirmed Theia-style mineralisation about 150 metres south of the current resource, with most of the best intercepts outside the pit shell.
- The June 2025 open-pit PFS shows an NPV8 of A$1.4 billion at A$4,250/oz, so any underground tonnes would sit on top of that base case.
- The Mandilla DFS is forecast for the March Quarter 2027, dependent on native title heritage surveys, while Theia Deeps is 18 of 21 holes complete.
Theia Deeps drilling hits 33m at 5.02g/t Au beneath the Theia pit
Diamond hole AMRCD377 has returned two wide, high-grade intercepts below the April 2026 Mineral Resource pit shell: 23m at 2.39g/t Au from 418m and 33m at 5.02g/t Au from 450m. Astral Resources (ASX: AAR) reported the results from its Theia Deeps program, part of the 100%-owned Mandilla Gold Project, located 70km south of Kalgoorlie in Western Australia.
Two further holes, AMRCD466 and AMRCD467, were drilled approximately 150 metres south of the current Theia Mineral Resource. Both confirmed extensions of south-west dipping, Theia-style gold mineralisation.
Two other zones of broad, lower-grade mineralisation sit deeper in AMRCD377. Aggregated, the four intercepts total 143m at 1.87g/t Au from 418m.
AMRCD377 was drilled 60 metres north-east of AMRCD378 on the same section. AMRCD378 was reported in the 17 August 2026 announcement and returned 52.75m at 4.67g/t Au from 445.25m, just beneath the base of the current Mineral Resource shell.
Two holes on one section, both showing wide, high-grade gold below the pit shell, is what you want to see when a company is testing whether a zone holds together. That continuity is central to the case for any future underground operation.
Marc Ducler, Managing Director, Astral Resources
“The standout is AMRCD377 with intercepts of 23m at 2.39g/t Au and 33m at 5.02g/t Au – below the current Mineral Resource shell. This is similar to the mineralisation intersected previously in AMRCD378, which intersected 52.75m at 4.67g/t Au, providing further evidence of a potentially significant high-grade zone beneath the current Theia Mineral Resource.”
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Underground potential below the Theia open pit
What the intercepts show
Early interpretations link the higher-grade results to zones of greater dilation (where rock has opened up) and an increasing frequency of quartz veining. The company says this could potentially support future extraction by underground mining methods below the economic base of the proposed Theia open pit.
Inside AMRCD377, the 23m zone includes 0.3m at 107.9g/t Au from 431.58m. The 33m zone includes 1.32m at 81.2g/t Au from 474.7m.
Why depth extensions matter
An open pit mine digs down from the surface in a wide hole, and works only while the ore is worth more than the cost of removing the rock above it. An underground mine follows the ore beneath, and can make sense where a zone is thick and high-grade enough to pay for the extra cost.
A Mineral Resource shell is the pit outline used to constrain the Mineral Resource estimate. Mineralisation below it is not captured in that pit-constrained estimate, which is why results below the shell matter.
Three points help put the results in context:
- Wide intercepts suggest a zone with real thickness, not just a thin vein.
- Higher grades can improve the economics of underground mining.
- Repeated hits on the same section (AMRCD377 and AMRCD378) help test whether the zone is continuous.
The Theia Deposit holds 1.4Moz within the Mandilla Mineral Resource of 1.74Moz (53.5Mt at 1.0g/t Au, April 2026).
Southern extension 150 metres beyond the Mineral Resource
AMRCD466 and AMRCD467 were drilled to test for dip extensions to the south-west of the main mineralised zone at Theia. Both confirmed south-west dipping Theia-style mineralisation, with most of the best intercepts outside the April 2026 pit shell.
| Hole | Interval | Grade | From (m) | Position vs pit shell |
|---|---|---|---|---|
| AMRCD466 | 42m | 0.89g/t Au | 285m | Outside |
| AMRCD466 | 6m | 13.2g/t Au | 595m | Not stated |
| AMRCD467 | 11.2m | 5.82g/t Au | 220.19m | Inside |
| AMRCD467 | 7.5m | 4.00g/t Au | 257.7m | Outside |
| AMRCD467 | 35.9m | 1.57g/t Au | 303.1m | Outside |
The 42m intercept in AMRCD466 is described as down-hole and located well outside the pit shell. In AMRCD467, the 7.5m, 13.7m (1.70g/t Au from 282.3m) and 35.9m intercepts are outside it, while only the 11.2m intercept sits inside.
All intervals are down-hole lengths, and the announcement does not state true widths.
AMRCD466 also returned 0.3m at 97.1g/t Au from 112.42m, and its 6m high-grade interval includes 0.5m at 153.6g/t Au from 596.88m.
Key drilling details:
- AMRCD467 was drilled 110m east of AMRCD466.
- The three holes (AMRCD377, AMRCD466 and AMRCD467) total 1,819.3m.
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Next steps for Mandilla, Spargoville and Feysville
Drilling continues across the company’s projects, with the status as follows:
- Theia Deeps: 18 of 21 holes (11,000m) complete.
- Theia Stage 1 RC in-fill: 28,350m completed of the 431-hole (44,400m) program.
- Spiders (Spargoville) and Kamperman (Feysville): pad preparation is scheduled for mid-October, allowing RC and DD to commence at the Spiders and Kamperman respectively during the December Quarter.
- Mandilla Definitive Feasibility Study (DFS): forecast for completion during the March Quarter 2027, with timing reliant on the completion of native title heritage surveys.
- Think Big (Feysville): the company is pursuing an early mining opportunity that could produce cash flow during the June Quarter 2027.
One inconsistency is worth flagging. Ducler’s comments refer to a phased 55-hole/10,000 metre RC program at Spargoville and a 3-hole/1,000 metre DD program at Kamperman, while the announcement body names the Spiders Deposit (Spargoville) and Kamperman. This article follows the body text.
What is the investment case behind Mandilla?
In June 2025, Astral announced a Preliminary Feasibility Study (PFS) for Mandilla, which also included the mining of gold deposits at Feysville. It was based on a standalone project of seven open pit mines feeding a 2.75Mtpa processing facility, producing 95koz per year for the first 12 years.
The PFS base case of A$4,250/oz gold demonstrated a Net Present Value (8% discount rate) of $1.4 billion. At A$6,250/oz, the company states the NPV8 increases to $2.9 billion.
The group’s consolidated Mineral Resource stands at 2.214Moz. The deeper results from Theia matter because the PFS is built on open pits, so any underground potential would sit beyond that base case.
For readers wanting the economics behind the open pit base case, our full explainer on Mandilla project economics walks through the 95,000oz annual production profile and the NPV sensitivity to gold price.
Ready to Learn More About Astral Resources’ Mandilla Gold Project?
Astral Resources’ Theia Deeps drilling has returned 33m at 5.02g/t Au beneath the planned open pit, pointing to potential high-grade underground mineralisation within the 100%-owned Mandilla Gold Project. With a Mineral Resource of 1.74Moz at Mandilla and a Definitive Feasibility Study forecast for the March Quarter 2027, the project continues to build momentum.
Explore the Astral Resources company profile and latest ASX updates to see how Theia Deeps, Spargoville and Feysville could shape the company’s growth.