Astral Resources NL (ASX:AAR) has increased its consolidated mineral resource to 2.07 million ounces of gold after delivering a 22% uplift at its flagship Mandilla Gold Project in Western Australia.
The updated Mandilla mineral resource estimate now stands at 54 million tonnes at 1.0g/t gold for 1.74 million ounces, up from 1.43 million ounces previously, adding 310,000 ounces to the inventory. The increase gives the company greater scale as it pushes ahead with study and permitting work.
Mandilla is located 70 kilometres south of Kalgoorlie and remains the dominant asset within Astral’s broader gold portfolio. With the inclusion of Feysville and Spargoville, the company’s total group resource has risen to 61.6 million tonnes at 1.0g/t for 2.072 million ounces.
The increase is particularly significant, as Astral continues to refine the project for development rather than relying solely on greenfields growth. The updated estimate was built using a 0.40g/t gold cut-off and pit shells based on a A$4,500 per ounce gold price, with cost assumptions aligned to the Mandilla pre-feasibility study released in June 2025.
“This update to the Mandilla Mineral Resource Estimate is an important precursor to the detailed mine design work that is now underway to support the Mandilla DFS. A key driver for this update was to understand the MRE’s response to the 12.5m x 12.5m in-fill drilling recently completed within the Stage 1 Theia open pit," Astral Resources’ managing director Marc Ducler said.
“Importantly, the outcome of the in-fill program was a very strong validation of the geological interpretation and estimation methodology. The metal variance in declared Mineral Resources from early January 2022 – where drill spacing in the equivalent area averaged 25m x 40m – increased by approximately 4%. The fact that both grade and ounces have increased by 5.2% and 4.2% respectively – demonstrates a strong confidence in our estimation methodology.
“In-fill drilling is ongoing at Theia, with a 23,000m program underway to continue progressing the remainder of Stage 1 to a 12.5m x 12.5m drill spacing, which will ensure the first 12 - 18 months of mine production is derived from the Measured Resource category."
Theia remains the cornerstone
At the heart of the update is the Theia deposit, which remains the cornerstone of Mandilla and now hosts 41.0 million tonnes at 1.1g/t gold for 1.39 million ounces. That marks an increase of 233,000 ounces and means Theia accounts for about 80% of the Mandilla resource.
Theia also delivered an inaugural Measured Resource of 1.3 million tonnes at 1.3g/t for 57,000 ounces following close-spaced infill drilling in part of the Stage 1 open pit. That higher-confidence category is an important step as Astral advances mine design and looks to support the early years of production with better-defined material.
Other deposits within Mandilla also contributed to the overall increase. Iris grew to 6.5 million tonnes at 0.8g/t for 159,000 ounces, while Eos increased to 3.7 million tonnes at 1.0g/t for 118,000 ounces. Hestia was revised to 2.4 million tonnes at 1.0g/t for 73,000 ounces.
Map of Mandilla Gold Project showing April 2025 optimised pit shell outlines and section locations on local area geology.
“When reported on a like-for-like basis with the April 2025 MRE using a A$3,500 gold price and 0.39g/t lower cut-off, the updated MRE at the flagship Theia deposit still increased by 15%," Ducler said.
“Pleasingly, the Astral Group MRE is now 2.07Moz, firmly cementing our status as a significant emerging gold producer in Western Australia.
“Notwithstanding the recent volatility in the gold price, the price is 100% higher than the design assumptions used in the June 2025 PFS. In this environment, and given our confidence that the Theia deposit remains open at depth, we are now evaluating an underground mining option for Theia.
“To that end, a diamond drill rig is currently undertaking a 6-hole (3,000-m) program targeting up to 175 metres of vertical depth extension across several sections below the central Theia deposit. This program, aiming to scope the potential scale of the Theia mineral system, has the potential to define substantial future growth potential if successful."
The resource update reinforces the broader development case for Mandilla by increasing the size of the inventory feeding into the definitive feasibility study. In practical terms, it gives Astral more ounces, more flexibility in mine design and a stronger platform from which to assess future production options.
What's next?
Detailed mine design work is underway as part of the Mandilla DFS, while drilling continues to upgrade more of the Stage 1 pit area to the Measured category. Astral is also testing for further growth at depth below Theia through a 6-hole, 3,000-metre diamond drilling program, with the deposit still open below the current resource envelope.
Alongside the DFS work, the company is progressing mining approvals and heritage clearance surveys.
“The work streams for the DFS and mining approvals continue to be advanced. Heritage clearance surveys are also currently in progress," Ducler said.
“At the same time, progress towards execution of the JV agreement at Feysville with MMS is continuing.
“Pending completion of planned heritage clearance surveys at Spargoville and the broader Kamperman area, the Astral exploration team is also looking forward to getting an RC rig back into our highly prospective exploration portfolio of tenements in the near future.”
Exploration activity is expected to continue across the broader portfolio, including Feysville and Spargoville, as Astral works to convert its expanding resource base into the next stage of project development.