HIGHLIGHTS
- Exceptional metallurgical characteristics of the Mandilla Gold Project reconfirmed by recent test- work undertaken on samples from the Hestia, Eos and Iris deposits.
- Metallurgical testing was completed under a range of grind sizes and under very modest cyanide concentrations reflecting typical process plant conditions.
- Outstanding results were achieved, with extremely high gravity gold recoveries and very rapid leaching. At a 212µm grind size, the final gold recoveries achieved after only eight hours of leaching were:
- For Hestia, 96.5% gravity recovery, 99.5% final recovery;
- For Eos, 17.9% gravity recovery, 98.8% final recovery; and
- For Iris,66.8% gravity recovery, 96.5% final recovery.
- Consistent with the results achieved previously at Theia, Mandilla’s flagship deposit, metallurgical results at Hestia, Eos and Iris demonstrate extremely high gold recoveries, fast leach kinetics and low reagent consumptions.
- Turning to exploration, the first phase of an in-fill RC program at Theia has recently been completed with 70 holes drilled for an aggregate 6,500 metres. The drill rig has relocated to the Feysville Gold Project to undertake a 34-hole (3,750 metres) program to test for extensions to the Kamperman deposit.
- Seven out of the 34 holes have already been completed; encouragingly, the first three holes, including a 200-metre step-out to the north and the two most north-eastern step-outs, have all intersected significant quartz and sulphide mineralisation which is a characteristic of the lithologies which host mineralisation elsewhere at Kamperman.
- Mineral Resource estimations are currently underway for Think Big, Rogan Josh and Kamperman – all at Feysville – and are expected to be reported later this month.
Astral Resources’ Managing Director Marc Ducler said: “The exceptional metallurgical results for Hestia, Eos and Iris continue to highlight the outstanding metallurgical characteristics of the Mandilla Gold Project. Typically, gold project studies in the Eastern Goldfields report initial metallurgical results based on 1,000ppm cyanide concentrations and 75µm grind sizes. The confidence in the Mandilla Gold Project gained from prior studies allowed us to successfully test much lower cyanide levels at much coarser grind sizes that would deliver very low processing costs yet still achieve sector-leading gold recoveries.
“To date, we have conducted 20 gravity and leach tests at Mandilla, with the gold remaining in the assayed tail averaging 0.02g/t Au. This demonstrates that the 95.7% gold recovery assumption used in the Scoping Study, while considered high by industry standards, is potentially conservative when considering the excellent metallurgical properties being demonstrated at Mandilla.
“These new results significantly de-risk Mandilla, confirming the ability to generate high gold recoveries in easily achievable, real-world processing plant conditions.
“This will positively impact the metrics and economics of the Mandilla Gold Project Pre-Feasibility Study which is expected to be completed in the June quarter 2025.
“I note that, in the Scoping Study announced on 21 September 2023, no contribution was included for Iris where a Mineral Resource of 115koz is currently mapped. However, in light of these metallurgical results as well as the increase in gold price since the Study was released, it is anticipated that ore from Iris may be included as part of the Pre-Feasibility Study.
“Turning to exploration, drilling activities are progressing well, with the latest phase of in-fill RC drilling at Theia completed. The drill rig has since been relocated to Feysville to complete further extensional and in-fill drilling at Kamperman with seven holes already completed. Importantly, step-out holes up to 200 metres further north of the current known extents of gold mineralisation have intersected significant quartz and sulphide mineralisation which is similar in characteristic to the lithologies which host gold mineralisation at Kamperman.
“With Mineral Resource Estimation work currently underway at Feysville, the team has also taken the opportunity to refine the geological models for the Hestia and Eos deposits. Updated MRE’s are now expected later this month for Think Big, Rogan Josh and Kamperman at Feysville, with Hestia and Eos to follow later in the December Quarter.”
Figure 1 – Map illustrating location of Mandilla and Feysville Gold Projects.
MANDILLA GOLD PROJECT
The Mandilla Gold Project 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 and 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 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.
In July 2023, Astral announced a Mineral Resource Estimate (MRE) of 37Mt at 1.1 g/t Au for 1.27Moz of contained gold1 for the Mandilla Gold Project.
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