Great Southern Mining Launches Diamond Drilling at Mt Dillon with Gold Fields-Backed Exploration in Northern Queensland

Diamond Drilling Program Underway at Mt Dillon Through Gold Fields Partnership

Great Southern Mining has commenced diamond drilling at the Mt Dillon target, a key step in exploring the Edinburgh Park Project. The program, consisting of up to 1,300 metres of drilling, is managed and funded by G-Ex Resources Ltd, a subsidiary of Gold Fields Ltd, one of the world’s leading gold producers. This partnership highlights Gold Fields’ confidence in the project’s potential and provides GSN with significant financial support through the earn-in joint venture agreement.

Drilling is expected to be completed within four to six weeks, focusing on geophysical targets identified by recent surveys. GSN Managing Director Matthew Keane noted that Mt Dillon is the highest-priority target at Edinburgh Park, featuring "compelling attributes including shallow IP anomalism beneath a preserved lithocap and multi-element anomalism consistent with epithermal and/or intrusion-related systems." The involvement of a major gold producer’s subsidiary underscores the strategic value of this asset in a region known for substantial gold deposits.

Strategic Location of Edinburgh Park Project in a Proven Gold District

The Edinburgh Park Project covers 1,447 square kilometres in northern Queensland, approximately 100 kilometres southeast of Townsville. The project is situated within a prolific gold region hosting significant deposits such as Ravenswood (~10 million ounces), Mt Leyshon (over 3 million ounces), and Mt Carlton (~2 million ounces). This regional setting evidences the district’s capacity to host large-scale gold mineralisation suitable for major mining operations.

GSN holds extensive land positions in renowned mining districts, including Laverton in Western Australia and northern Queensland goldfields. All projects are within 40 kilometres of operating mills and major mining operations, offering logistical advantages for future mineral processing and development. The Edinburgh Park Project’s location in a prolific goldfields region and proximity to existing infrastructure enhances its potential for resource definition and development.

Geophysical Data Validates Mt Dillon as a Prime Exploration Target

Mt Dillon’s prospectivity is supported by strong geophysical data from 2025 induced polarisation (IP) surveys. Gradient array IP surveys revealed a large chargeability anomaly beneath Mt Dillon, indicating potential sulphide mineralisation associated with a preserved intrusive system. A 2D IP section showed a chargeable response 200 to 300 metres below surface, consistent with mineralisation depths typical of porphyry-style systems.

Underlying the chargeability anomaly is a resistivity anomaly, likely representing pervasive hydrothermal alteration within a porphyry system. The combination of shallow chargeability and resistivity anomalies provides a robust technical rationale for the drilling program, targeting a chargeability anomaly exceeding 20 millivolts.

Lithocap Preservation and Alteration Mineralogy at Mt Dillon

Mt Dillon is characterized by a silicified lithocap consisting of volcanic rocks from the Lizzie Creek Volcanics. The area exhibits several square kilometres of intensely altered felsic volcanics trending north-northeast, with alteration styles ranging from phyllic to advanced argillic. The alteration intensity, metal depletion in surface samples, and preserved topography align with the leached lithocap zone of a large intrusive system, indicating significant deeper mineralisation potential.

The Mt Dillon outlier features strong clay-pyrite-silica alteration with abundant sulphides, mainly pyrite, at concentrations between 3% and 10%. Surface mineral assemblages correspond to a high-temperature (>300°C), low-pH hydrothermal system typical of high sulphidation epithermal environments. Multi-element geochemical anomalies include bismuth, indium, molybdenum, lead, selenium, antimony, tungsten, and tellurium, supporting the epithermal and intrusion-related mineralisation model.

Global Examples of Lithocap-Covered Copper-Gold Deposits Support Exploration Model

GSN’s exploration approach at Mt Dillon draws on global precedents where large copper-gold deposits are concealed beneath lithocaps. Notable examples include Quebradona in Colombia (AngloGold Ashanti) with 4.26 million tonnes of copper and 7 million ounces of gold, and Valeriano in Chile (ATEX Resources) with 7.1 million tonnes of copper and 9.6 million ounces of gold, both under lithocap features. These cases demonstrate that lithocap preservation can indicate significant mineralisation at depth.

Additional international analogues include the Lepanto epithermal and Far Southeast porphyry deposits in the Philippines (Lepanto Consolidated Mining), collectively containing more than 20 million ounces of gold and over 4.5 million tonnes of copper. The geological and mineralisation styles at these world-class deposits align with Mt Dillon’s characteristics, reinforcing the exploration rationale.

Gold Fields Earn-In Agreement and Funding Structure

The Edinburgh Park Project’s exploration is financed through a strategic earn-in joint venture with Gold Fields Ltd. G-Ex Resources Ltd, Gold Fields’ wholly owned subsidiary, manages the exploration and holds an option to invest up to A$15 million to earn a 75% interest. This structure provides GSN with funding and technical expertise while allowing Gold Fields to assess the project’s potential and determine future involvement.

This earn-in model aligns both parties’ interests: Gold Fields gains exposure to a promising early-stage asset in a prolific gold region without immediate full acquisition, while GSN retains upside potential and benefits from exploration funding without proportional capital outlay. Gold Fields’ participation validates the technical merit of GSN’s targeting and adds credibility to the Edinburgh Park exploration program.

Planned Exploration and Survey Programs for 2026-2027

GSN Managing Director Matthew Keane stated that "the scale and prospectivity of the Edinburgh Park Project are expected to generate numerous targets beyond Mt Dillon," indicating that this initial drill test is part of a broader exploration strategy. Additional geochemical and geophysical surveys are scheduled for 2026 and 2027 to identify new drill-ready targets.

These future surveys will build on the 2025 induced polarisation work and likely include further mapping, geochemical sampling, and additional geophysical techniques to detect buried mineralisation. This multi-year exploration plan reflects GSN and Gold Fields’ commitment to thoroughly evaluate the 1,447 square kilometre project area and maximize discovery potential.

Diverse Mineralisation Styles Targeted at Edinburgh Park

The Edinburgh Park Project targets multiple mineralisation styles typical of northern Queensland goldfields, including high and low sulphidation epithermal gold-silver systems within Permian volcanic rocks, as well as porphyry gold-copper-molybdenum and intrusion-related gold mineralisation in Carboniferous basement geology. This geological diversity provides multiple exploration pathways, enhancing the chances of discovering economic mineralisation across the project.

The Mt Dillon target is interpreted as prospective for intrusive-related gold systems based on geological, geochemical, and geophysical data. The broader project also includes areas prospective for epithermal mineralisation, suggesting future exploration phases may reveal additional targets with varying mineralisation styles. This multi-style approach aligns with best-practice exploration strategies in the region.

Competent Person Endorsement and Technical Integrity

Exploration data and targeting methodologies at Edinburgh Park have been compiled and reviewed by Matthew McCarthy, an employee of Great Southern Mining Limited and a Competent Person under the JORC Code 2012. McCarthy has approved the inclusion of exploration results in this update, ensuring technical credibility and compliance with professional standards.

The involvement of a qualified Competent Person meets ASX Listing Rules and JORC Code requirements, providing investors with assurance that disclosed exploration information is accurate, reliable, and presented according to industry best practices.