Great Southern Mining Drills Deeper Than Planned as Gold Fields Funds Assay Wait
Key Takeaways
- Great Southern Mining has completed its maiden Mt Dillon campaign, drilling two holes for 1,534.9m of core at Edinburgh Park in north Queensland.
- Both holes ran past plan: EDDDAD00015 reached 762.1m against 575m, and EDDDAD00016 reached 772.8m against 700m.
- First assays are due late-October to early-November, and they alone will show whether the lithocap target holds economic mineralisation.
- Core logging shows a 60-80m fault zone, widespread disseminated pyrite and breccias with up to 5% pyrite, which the company calls consistent with an intermediate sulphuration epithermal system.
- Gold Fields funds the exploration and can spend up to A$15M to earn 75%, which limits GSN's direct cost exposure on a 1,447km² project.
Mt Dillon diamond drilling completed at Edinburgh Park
Two holes, 1,534.9m of core and no assay results yet. Great Southern Mining (ASX: GSN) has completed the maiden Mt Dillon diamond drilling campaign within the Edinburgh Park Project in north Queensland, and both holes were extended well beyond their planned depths.
Core processing is nearing completion, with first assay results expected in late-October to early-November, based on current estimated laboratory turnaround times. Those assays are the next near-term catalyst, because the company states that any concentration of economic mineral assemblages will be determined by core assays.
Exploration at Edinburgh Park is being managed and funded by G-Ex Resource Ltd, a wholly owned subsidiary of Gold Fields Ltd.
Matthew Keane, Managing Director
“…This is a big target with multiple geological facets that make it attractive for a large-scale IRGS discovery.”
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Both holes drilled deeper than planned
Hole EDDDAD00015 was planned to 575m and extended to 762.1m. Hole EDDDAD00016 was planned to 700m and extended to 772.8m. The announcement does not state why the holes were extended.
| Hole ID | Planned depth | Actual depth | Dip | Azimuth |
|---|---|---|---|---|
| EDDDAD00015 | 575m | 762.1m | -45 | 080 |
| EDDDAD00016 | 700m | 772.8m | -45 | 055 |
Both holes were drilled from the same pad. They were designed to test broad, partly overlapping chargeability and resistivity anomalies from Induced Polarisation (IP) surveys, beneath the interpreted argillic to advanced argillic lithocap. IP is a geophysical method that measures how the ground responds to an electrical current.
What is an intrusive related gold system (IRGS) and a lithocap?
An intrusive related gold system (IRGS) is a gold deposit style linked to hot fluids released from an intrusion of molten rock. A lithocap is a large zone of intensely altered rock at surface, formed by acidic fluids, and Mt Dillon is interpreted to host a preserved lithocap.
The company notes that several large-scale copper-gold deposits have been discovered below surface lithocaps globally:
- Quebradona (Colombia, AngloGold Ashanti): 4.26Mt copper and 7.0Moz gold contained
- Valeriano (Chile, ATEX Resources): 7.1Mt copper and 9.6Moz gold contained
- Lepanto and Far Southeast (Philippines, Lepanto Consolidated Mining): +20Moz gold and +4.5Mt copper contained
These are analogues for the style of target, not predictions for Mt Dillon. For you as an investor, a lithocap target offers scale potential, but the outcome hinges entirely on assay results.
Core logging reveals epithermal system features
Geological logging of the core recorded several features:
- A 60-80m wide chaotic fault zone near the top of both holes
- Mixed intrusive and volcanic sequences dominated by phyllic-altered (silica-sericite-pyrite) rocks
- Disseminated pyrite (iron sulphide) throughout both holes, with 1-3% pyrite in the lower half of EDDDAD00015
- Discrete hydrothermal breccia zones with sulphide contents of up to 5% pyrite
The company says the alteration assemblages, broad zones of disseminated sulphides and hydrothermal brecciation are consistent with an intermediate sulphuration epithermal system.
Treat this carefully. This is visual logging, not assay data, and pyrite percentages are not gold grades.
Province-scale project with Gold Fields funding
Edinburgh Park covers 1,447km², approximately 100km southeast of Townsville. The region is known for large-scale epithermal and intrusion related gold systems, including Ravenswood (~10Moz), Mt Leyshon (+3Moz) and Mt Carlton (~2Moz). These are regional context only.
Under an earn-in joint venture, Gold Fields can spend up to A$15M to earn a 75% interest in the project. Because Gold Fields funds the exploration, GSN’s direct cost exposure to this work is reduced, while the announcement frames the project as having discovery potential.
Other work continues, including gravity surveys around the Edinburgh Castle target area and IP surveys at the Rhyolite Hill target. Further geochemical and geophysical surveys through the remainder of 2026 and into 2027 are expected to generate the next wave of potential drill targets.
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What investors should watch next
Three developments will shape the next phase:
- First assay results, expected in late-October to early-November
- Results from the gravity and IP surveys
- Potential new drill targets from surveys expected through 2026 and into 2027
Managing Director Matthew Keane said GSN considers Edinburgh Park prospective for large-scale systems, “with exploration still in its infancy.” Until the assays arrive, the geology is encouraging in style but unproven in grade.
Ready to Learn More About the Mt Dillon Target at Edinburgh Park?
Great Southern Mining has completed its maiden Mt Dillon diamond drilling, with two holes totalling 1,534.9m testing a lithocap target for a large-scale intrusion related gold system. With Gold Fields funding the exploration and first assays expected in late-October to early-November, the next catalyst is close.
Explore the Great Southern Mining company profile on Discovery Alert to see the latest announcements and project details. Stay informed before the assay results arrive.