Mandilla Gold Project
Flagship Project
Astral Resources 100%
The Mandilla Gold Project (Mandilla) is situated in the northern Widgiemooltha greenstone belt, approximately 70 kilometres south of the significant mining centre of Kalgoorlie, Western Australia.
The area hosts world-class deposits such as the Golden Mile Super Pit in Kalgoorlie owned by Northern Star Resources Limited (ASX: NST) and the St Ives Gold Mine south of Kambalda, owned by Gold Fields Limited, as well as the substantial Beta Hunt Gold Mine owned by Westgold Resources Limited (ASX: WGX).
Mandilla is covered by existing Mining Leases which are not subject to any third‐party royalties other than the standard WA Government gold royalty.
The Mandilla Gold Project includes the Theia, Iris, Eos and Hestia deposits.
Gold mineralisation at Theia and Iris is comprised of structurally controlled quartz vein arrays and hydrothermal alteration close to the western margin of the Emu Rocks Granite and locally in contact with sediments of the Spargoville Group.
Significant NW to WNW-trending structures along the western flank of the project are interpreted from aeromagnetic data to cut through the granitic intrusion. These structures are considered important in localising gold mineralisation at Theia, which has a mineralised footprint extending over a strike length of more than 1.6km.
A second sub-parallel structure hosts gold mineralisation at the Iris deposit. The mineralised footprint at Iris extends over a strike length of approximately 600 metres, combining with Theia to form a mineralised zone extending over a strike length of more than 2.2 kilometres.
At Eos, located further to the south-east, a relatively shallow high-grade mineralised palaeochannel deposit has been identified which extends over a length of approximately 600 metres. A primary gold source is also present, with further drilling required to determine both the nature and structural controls on the mineralisation and its extent.
Mineralisation delineated over approximately 800 metres of strike at the Hestia deposit, located approximately 500 metres west of Theia, is associated with a shear zone adjacent to a mafic/sediment contact, interpreted to be part of the major north-south trending group of thrust faults known as the Spargoville Shear Corridor.
Locally, the Spargoville Shear Corridor hosts the historically mined Wattle Dam gold mine (266koz at 10.6g/t Au) and, further to the north, the Ghost Crab/Mt Marion mine (>1Moz).
The mineralisation at Hestia, which is present in a different geological setting to bedrock mineralisation at Theia and Iris, remains open both down-dip and along strike.
On 3 April 2025, Astral announced an update to the Mandilla Mineral Resource Estimate (MRE) 42Mt at 1.1 g/t Au for 1.42Moz of contained gold1 for the Mandilla Gold Project.
Metallurgical testing undertaken on each of the main deposits at Mandilla – Theia, Iris, Eos and Hestia – has demonstrated high gravity recoverable gold, fast leach kinetics and exceptional overall gold recoveries with low reagent consumptions and coarse grinding2,3,4.
In September 2023, Astral announced the results of a Scoping Study for Mandilla (Scoping Study) which – based on a standalone project comprising three open pit mines feeding a 2.5Mtpa processing facility, producing 80 to 100koz per year, and incorporating a gold price of A$2,750 – has a Net Present Value (8% discount rate) of $442 million5.
The Scoping Study did not include any contribution from Astral’s nearby 100%-owned Feysville Project, which currently hosts a 196koz MRE6.
Astral is currently progressing a Pre-Feasibility Study (PFS) for the Mandilla Gold Project which is expected to be finalised during the June 2025 Quarter.
Scoping Study
In September 2023, Astral announced the results of a Scoping Study for Mandilla (Scoping Study) which – based on a standalone project comprising three open pit mines feeding a 2.5Mtpa processing facility, producing 80 to 100koz per year, and incorporating a gold price of A$2,750 – has a Net Present Value (8% discount rate) of $442 million7.
The Scoping Study confirmed the potential for Astral’s flagship Mandilla Gold Project to become a highly profitable standalone gold operation. Mandilla is situated in the premier Goldfields region of Western Australia and is firmly established as one of the best free-milling, open pit Resources in this district in both scale and quality of project.
The Study outlined compelling financial metrics for a Mandilla development, with projected free cash-flows of approximately $740 million over a life-of-mine of 11 years and a payback period of less than a year for total pre-production capital expenditure of approximately $191 million.
The Study financials were modelled using a gold price assumption of A$2,750 per ounce, which is significantly lower than the spot price has been for the past six months and used a five-stage open pit design based on a A$2,100 per ounce pit optimisation. This further highlights the potential upside for a Mandilla development.
A copy of the Scoping Study can be accessed via this link.
Astral is currently progressing a Pre-Feasibility Study (PFS) for the Mandilla Gold Project which is expected to be finalised during the June 2025 Quarter.
Mineral Resource Estimate (JORC 2012)
On 3 April 2025, the Astral announced an updated JORC 2012 Mineral Resource Estimate (MRE) of 42 million tonnes at 1.1g/t Au for 1.43 million ounces of contained gold (April 2025 MRE), encompassing the cornerstone Theia deposit and the Iris, Eos and Hestia deposits.
The MRE was prepared by independent consultant Cube Consulting in accordance with the JORC Code (2012 Edition).
The April 2025 MRE has been estimated using a 0.39g/t Au lower cut-off and constrained within pit shells derived using a gold price of A$3,500 per ounce.
The locations of the optimised pit shells based on a gold price of AUD$3,500 per ounce are set out in plan view in Figure 2 below.
The Mandilla MRE is summarised in Table 1 below, with a detailed breakdown by deposit provided in Table 2 and a grade and tonnage sensitivity analysis by cut-off grade provided in Table 3.
Table 1 – Mandilla MRE (April 2025)
| Mineral Resource Estimate for the Mandilla Gold Project (Cut-Off Grade >0.39g/t Au) | |||
| Classification | Tonnes (Mt) | Grade (g/t Au) | Au Metal (koz) |
| Indicated | 30.6 | 1.1 | 1,034 |
| Inferred | 10.9 | 1.1 | 392 |
| Total | 41.5 | 1.1 | 1,426 |
| The preceding statement of Mineral Resources conforms to the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (JORC Code) 2012 Edition. All tonnages reported are dry metric tonnes. Minor discrepancies may occur due to rounding to appropriate significant figures. | |||
Table 2 – Mandilla MRE (April 2025) by source
| Deposit | Classification | Tonnes (Mt) | Grade (g/t Au) | Au Metal (koz) |
| Theia | Indicated | 24.5 | 1.1 | 832 |
| Inferred | 8.8 | 1.2 | 323 | |
| Total | 33.3 | 1.1 | 1,154 | |
| Iris | Indicated | 2.8 | 0.8 | 68 |
| Inferred | 1.6 | 0.8 | 40 | |
| Total | 4.3 | 0.8 | 108 | |
| Eos | Indicated | 1.2 | 1.6 | 59 |
| Inferred | 0.4 | 1.1 | 13 | |
| Total | 1.5 | 1.5 | 72 | |
| Hestia | Indicated | 2.2 | 1.1 | 76 |
| Inferred | 0.2 | 2.1 | 15 | |
| Total | 2.4 | 1.2 | 91 | |
| Total | 41.5 | 1.1 | 1,426 | |
| All tonnages reported are dry metric tonnes. Minor discrepancies may occur due to rounding to appropriate significant figures. | ||||
Table 3 – Mandilla MRE (April 2025) by cut-off grade
| Cut-off grade (g/t Au) | Tonnes (Mt) | Grade (g/t) | Au Metal (koz) |
| 0.30 | 48.6 | 1.0 | 1,505 |
| 0.35 | 44.9 | 1.0 | 1,467 |
| 0.39 | 41.5 | 1.1 | 1,426 |
| 0.40 | 41.1 | 1.1 | 1,420 |
| 0.45 | 37.4 | 1.1 | 1,370 |
| 0.50 | 34.1 | 1.2 | 1,320 |
| All tonnages reported are dry metric tonnes. Minor discrepancies may occur due to rounding to appropriate significant figures. | |||
Theia Deposit
Theia remains the cornerstone deposit at Mandilla, with the MRE estimated at 33.3Mt at 1.1g/t Au for 1.15Moz of contained gold , including 24.5Mt at 1.1g/t for 832koz of contained gold in the Indicated Mineral Resource category.
Theia represents approximately 81% of the Mandilla MRE.
Figure 3 below shows the Mineral Resource for Theia within the optimised pit shell in cross-section.
Iris Deposit
The Iris deposit hosts a MRE of 4.3Mt at 0.8g/t Au for 108koz of contained gold, including 2.8Mt at 0.8g/t for 68koz of contained gold in the Indicated Mineral Resource category.
Figure 4 below shows the Mineral Resource for Iris within the optimised pit shell in cross-section.
Eos Deposit
The Eos deposit hosts a MRE of 1.5Mt at 1.5g/t Au for 72koz of contained gold.
Of this, the palaeochannel deposit MRE, which now includes a southern zone, is estimated at 0.69Mt at 2.09g/t Au for 46koz of contained gold.
The bedrock Eos MRE is estimated at 0.8Mt at 0.9g/t Au for 25koz of contained gold.
Figure 5 below, shows a cross-section encompassing both the Eos paleochannel and the fresh rock MRE.
Hestia Deposit
The Hestia Deposit hosts a MRE of 2.4Mt at 1.2g/t Au for 91koz of contained gold, including 2.2Mt at 1.1g/t for 76koz of contained gold in the Indicated Mineral Resource category.
Figure 6 below, shows a longitudinal projection of Hestia.
- Mandilla JORC 2012 Mineral Resource Estimate: 31Mt at 1.1g/t Au for 1,034koz Indicated Mineral Resources and 11Mt at 1.1g/t Au for 392koz Inferred Mineral Resources. See ASX Announcement 3 April 2025. ↩︎
- ASX Announcement 6 June 2022 “Outstanding metallurgical test-work results continue to de-risk Mandilla” ↩︎
- ASX Announcement 17 September 2024 “Outstanding metallurgical results further de-risk Mandilla” ↩︎
- ASX Announcement 5 March 2025 “Further Outstanding Metallurgical Recoveries from Theia” ↩︎
- ASX Announcement 21 September 2023 “Mandilla Gold Project – Kalgoorlie, WA. Positive Scoping Study” ↩︎
- Feysville JORC 2012 Mineral Resource Estimate: 4Mt at 1.3g/t Au for 144koz Indicated Mineral Resources and 1Mt at 1.1g/t Au for 53koz Inferred Mineral Resources (refer to Astral ASX announcement dated 1 November 2024). ↩︎
- ASX Announcement 21 September 2023 “Mandilla Gold Project – Kalgoorlie, WA. Positive Scoping Study” ↩︎