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Astral Resources Extends Theia Gold Mineralisation 250m Below Mandilla Resource

BY WILLIAM HADRIAN ON JULY 14, 2026

Astral Resources NL

  • ASX Code: AAR
  • Market Cap: $207,120,245
  • Shares On Issue (SOI): 1,801,045,606
  • This is a special feature article produced for our partner.

    Astral Resources Drills Deeper, Extends Theia Mineralisation Below 1.4Moz Resource Shell

    Astral Resources Theia gold deposit deep drilling results at Mandilla have captured significant market attention, with Astral Resources NL (ASX: AAR) reporting new deep diamond drilling results from the Theia Deposit at its 100%-owned Mandilla Gold Project, approximately 70km south of Kalgoorlie in Western Australia.

    According to the ASX announcement dated 14 July 2026, results from two additional deep holes confirm broad gold mineralisation within and below the April 2026 Mineral Resource shell at Theia, with mineralisation now intersected up to 250 metres beneath the current pit shell and remaining open at depth.

    Both reported holes, AMRCD260 and AMRCD261, form part of an expanded 12-hole, 7,500-metre deep diamond drilling program. Nine holes have now been completed, up from an original 6-hole, 3,000-metre design, reflecting continued success in identifying additional mineralisation below the cornerstone 1.4Moz Theia resource.

    What the New Assay Results Are Saying

    AMRCD260: Validating the Model and Extending Mineralisation 250m Below the Shell

    Hole AMRCD260 is the deeper of the two reported holes, reaching 663.9 metres down-hole.

    According to Astral Resources NL, the hole provides both confirmation of existing Inferred Mineral Resources within the April 2026 pit shell and evidence for a substantial depth extension below the current model.

    Within and around the resource shell, key intersections include:

    • 16.52m at 1.54 g/t Au from 272.48m, including 0.35m at 28.5 g/t Au
    • 17.0m at 0.65 g/t Au from 295.0m
    • 17.0m at 0.45 g/t Au from 319.0m
    • 52.60m at 1.48 g/t Au from 389.4m, including:
      • 0.45m at 17.9 g/t Au from 408.2m
      • 0.3m at 16.4 g/t Au from 414.94m
      • 0.3m at 18.3 g/t Au from 427.77m

    Astral Resources NL reports that this 52.60m at 1.48 g/t Au zone correlates well with the existing Inferred Mineral Resource model at the base of the current pit shell and confirms continuity of mineralisation.

    Below the April 2026 Mineral Resource shell, AMRCD260 then intersected new zones at depth that extend the known mineral system by up to 250 metres:

    • 7.0m at 5.22 g/t Au from 583.0m, including 0.3m at 114.7 g/t Au
    • 43.86m at 0.87 g/t Au from 605.0m, including:
      • 0.3m at 61.5 g/t Au from 605.78m
      • 0.3m at 13.7 g/t Au from 645.43m

    Visible gold was also logged at approximately 643m and 645m down-hole.

    These lower intersections are described in the report as a "potentially significant extension" of Theia mineralisation at depth, demonstrating that mineralisation continues well below the current resource envelope.

    AMRCD261: High-Grade Zone Outside the Shell and a Hole Ending in Mineralisation

    Hole AMRCD261, drilled further south along the Theia deposit, is highlighted in the ASX report as particularly important for growth potential outside the existing Mineral Resource shell.

    Key intersections include:

    • 54.0m at 2.38 g/t Au from 316.0m, including:
      • 1.0m at 10.8 g/t Au from 329.0m
      • 0.3m at 48.6 g/t Au from 332.7m
      • 0.88m at 73.2 g/t Au from 358.88m
    • 5.0m at 2.72 g/t Au from 582.0m, including 1.0m at 11.9 g/t Au
    • 14.77m at 0.78 g/t Au from 601.13m

    According to the announcement, on this particular cross-section no mineralisation or resource is currently modelled in the 150 metres immediately above the base of the April 2026 Resource shell.

    The 54.0m at 2.38 g/t Au from 316.0m intersection therefore represents a substantial new lode outside the defined resource, and it is described as extending Theia mineralisation down-dip to the south beyond the current model.

    Furthermore, AMRCD261 also ended in mineralisation, with:

    • 5.0m at 2.72 g/t Au from 582.0m
    • 14.77m at 0.78 g/t Au from 601.13m

    Visible gold was logged on the non-sample side of the core at 603.33m down-hole.

    For investors, a hole that terminates in mineralisation generally indicates that the drill rig stopped before the mineral system was fully defined at depth. According to Astral Resources NL, this supports further drilling to test the system further down-dip.

    Key Intersection Summary

    The key intersections reported from the two deep holes are summarised below.

    Hole ID From (m) Interval (m) Grade (g/t Au) Context relative to April 2026 shell
    AMRCD260 272.48 16.52 1.54 Within / near current MRE model
    AMRCD260 295.0 17.0 0.65 Within / near current MRE model
    AMRCD260 319.0 17.0 0.45 Within / near current MRE model
    AMRCD260 389.4 52.60 1.48 Within April 2026 Resource pit shell
    AMRCD260 583.0 7.0 5.22 Up to ~250m below base of shell
    AMRCD260 605.0 43.86 0.87 Up to ~250m below base of shell
    AMRCD261 316.0 54.0 2.38 Outside April 2026 Resource shell
    AMRCD261 582.0 5.0 2.72 Below shell, hole ended in mineralisation
    AMRCD261 601.13 14.77 0.78 Below shell, hole ended in mineralisation

    Two More Holes With Assays Pending and Visually Encouraging Geology

    Alongside AMRCD260 and AMRCD261, the ASX announcement highlights two additional deep diamond holes with assays pending: AMRCD376 and AMRCD262.

    According to Astral Resources NL, both holes display geological characteristics consistent with the Theia gold system, based on logging of quartz veins, sulphide minerals and occurrences of visible gold.

    AMRCD376: Extensive Veining and Sulphides East of AMRCD260

    Hole AMRCD376 is located approximately 170 metres east of AMRCD260 on the same cross-section.

    Geological logging recorded:

    • Broad alteration zones
    • Quartz veining with variable vein percentages
    • Abundant pyrite and other sulphides
    • Multiple logged occurrences of visible gold

    The vein percentages and visible gold observations are reported to correlate with known Inferred Mineral Resources on this section. Consequently, Astral Resources NL notes that this provides support for possible continuation of mineralisation further down-dip, pending assay confirmation.

    AMRCD262: Potential 230m Vertical Extension Below the Shell

    Hole AMRCD262 sits 50 metres east of AMRCD261 on the same section. Logging indicates:

    • Quartz, sulphides and visible gold starting within the April 2026 Resource pit shell
    • A broad alteration and veining zone extending to around 230 metres below the shell
    • Multiple intervals where quartz vein percentages and visible gold observations mirror those seen in mineralised zones elsewhere at Theia

    Based on these logged features, Astral Resources NL describes AMRCD262 as indicating a potentially wide zone of Theia-style mineralisation extending well beyond current resource limits, subject to assay results.

    "The Theia Deeps drill program continues to demonstrate that Theia has significant growth potential beyond the current resource, while also confirming mineralisation within the current pit shell," said Marc Ducler, Managing Director of Astral Resources NL.

    "Further south, AMRCD261 has also demonstrated potential for growth at Theia, returning an intercept of 54.0m at 2.38g/t Au from 316.0m, with this newly identified mineralisation located outside the April 2026 Mineral Resource shell. It is important to note that this hole ended in mineralisation, with visible gold observed on the non-sample side of the core at 603.33m."

    Educational Section: Understanding Visible Gold and Its Role in This Program

    What Is Visible Gold?

    In most gold deposits, gold is too fine to see with the naked eye and must be measured by laboratory assays.

    Visible gold refers to gold grains that are large enough to be seen directly in drill core or rock samples without magnification. Geologists record these occurrences in core logs as qualitative observations.

    Why Is Visible Gold Relevant at Theia?

    At Theia, Astral Resources NL reports a strong correlation between:

    • Logged visible gold
    • Higher quartz vein percentages
    • Elevated gold grades in laboratory assays

    This correlation means that, in this particular deposit, where geologists see visible gold and dense quartz veining, there is a reasonable historical association with economic grades once assays are completed.

    This is why the company specifically highlights visible gold in holes AMRCD376 and AMRCD262, even though assays are not yet available. However, Astral Resources NL also includes repeated cautionary statements:

    Visual estimates of mineral abundance should never be considered a proxy or substitute for laboratory analyses where concentrations or grades are the factor of principal economic interest.

    For investors, the practical interpretation is that visible gold and veining patterns can be considered early indicators of potential mineralisation but cannot be treated as confirmed grade or tonnage until supported by assays.

    Glossary of Key Technical Terms

    Term Plain-language explanation
    Diamond drilling (DD) A drilling method that uses a diamond-tipped bit to cut a cylindrical core of rock for detailed geological logging and sampling.
    Reverse circulation (RC) A drilling technique that uses compressed air to return rock chips to the surface through the drill pipe for sampling.
    Mineral Resource Estimate (MRE) A formal estimate of how much mineralised material is present in a deposit, and at what grade, prepared under the JORC Code.
    Inferred Resource The lowest confidence category of Mineral Resource, where there is enough data to suggest mineralisation but not enough for detailed mine planning.
    g/t Au Grams of gold per tonne of rock, the standard measure of gold grade.
    Pit shell A computer-generated outline of a potential open-pit mine, used to define which parts of the deposit might be economic at a given gold price.
    Quartz vein A sheet-like body of quartz that fills fractures in the rock, often hosting gold and sulphide minerals in deposits like Theia.
    Pyrite / pyrrhotite / galena Common sulphide minerals that frequently occur with gold. Their presence can indicate the right geological environment for gold mineralisation.

    Resource Foundation: Mandilla's Current Scale

    The deep drilling results reported by Astral Resources NL sit on top of an already defined Mineral Resource and Ore Reserve base at Mandilla and across the group.

    Group Mineral Resource Estimate

    According to the April 2026 resource update, the consolidated JORC 2012 Mineral Resource Estimate for Astral Resources NL is as follows:

    Project Measured (Moz) Indicated (Moz) Inferred (Moz) Total (Moz) Average grade (g/t Au)
    Mandilla 0.057 1.092 0.588 1.736 1.0
    Feysville 0 0.144 0.053 0.196 1.2
    Spargoville 0 0.081 0.058 0.139 1.4
    Total 0.057 1.317 0.698 2.072 1.0

    Mandilla, which includes the Theia, Iris, Eos and Hestia deposits, accounts for 1.736Moz of the group total, with Theia itself described as a 1.4Moz deposit.

    Group Ore Reserve Estimate

    The group's Probable Ore Reserves, supporting the June 2025 Mandilla Preliminary Feasibility Study (PFS), are summarised as:

    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

    These Reserves are a subset of the Mineral Resource and formed the basis of the PFS production and financial outcomes.

    Mandilla PFS and Broader Project Context

    The Mandilla PFS, released in June 2025, modelled:

    • A standalone operation with seven open-pit mines across Mandilla and Feysville
    • A 2.75Mtpa processing plant
    • Average production of 95,000 ounces per year for the first 12 years

    Using a base-case gold price of $4,250/oz, the PFS estimated a Net Present Value (NPV8) of $1.4 billion. At a higher price scenario of $6,250/oz, the NPV8 was reported at $2.9 billion.

    Metallurgical testwork across Theia, Iris, Eos and Hestia indicated:

    • High gravity-recoverable gold
    • Fast leach kinetics
    • High overall gold recoveries
    • Low reagent consumption
    • Coarse grind size potential

    These attributes are typically considered favourable for processing economics and form part of the rationale for advancing the project towards a Definitive Feasibility Study (DFS). In this context, any additional Mineral Resources that may be defined from the Astral Resources Theia gold deposit deep drilling results at Mandilla could, if converted and scheduled, provide optionality for future study updates.

    Current and Planned Work Programs

    The ASX announcement outlines a broad suite of ongoing and planned activities at Mandilla and across the Astral Resources NL portfolio.

    Mandilla and Theia Deeps

    • Deep diamond drilling at Theia Deeps

      • 9 of 12 deep holes completed in the expanded 7,500m program
      • Additional holes being planned to:
        • Convert newly intersected mineralisation into Inferred Resources
        • Test the extent of Theia mineralisation up and down-dip
    • Stage 1 in-fill drilling at Theia

      • 140 holes for 13,750m completed
      • Total planned program: 431 holes for 44,400m
      • Objective: improve resource classification within the Stage 1 open pit for future mine planning
    • Sterilisation drilling

      • Continuing at Mandilla, subject to heritage clearance surveys

    Feysville and Spargoville

    • Reverse circulation and diamond drilling planned for

    Ready to Dig Deeper Into Astral Resources' Mandilla Gold Project?

    With mineralisation now confirmed up to 250 metres below the current resource shell, holes ending in gold, and a 2.07Moz group resource underpinning a PFS that already points to a $1.4 billion NPV8, Astral Resources NL (ASX: AAR) is making a compelling case for scale at Mandilla. For investors looking to understand the full scope of the Theia Deeps program, the broader Mandilla project, and what comes next on the path towards a Definitive Feasibility Study, head to the Astral Resources website to explore the latest updates and announcements.

    Stock Codes: ASX: AAR

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