Great Southern Mining starts Gold Fields-funded Mt Dillon drilling

Great Southern Mining (ASX: GSN) has started diamond drilling at the Mt Dillon target within its Edinburgh Park project in northern Queensland. The program, which totals up to 1,300 metres, is the first test of the project’s highest-priority prospect.

The work is being managed and funded by G-Ex Resources, a wholly owned subsidiary of Gold Fields (NYSE: GFI). Under an earn-in arrangement, Gold Fields can spend up to A$15 million to earn a 75% project interest. The initial drilling is the first step toward that spending commitment.

Edinburgh Park sits about 100 kilometres southeast of Townsville. The project targets epithermal gold-silver systems, porphyry gold-copper-molybdenum mineralisation, and intrusion-related gold systems within its volcanic and basement geology. Mt Dillon is considered prospective for IRG systems specifically.

Drilling is designed to test shallow chargeability and resistivity anomalies identified by earlier induced polarisation surveys beneath a preserved silicified lithocap. Gradient array IP surveying completed in early 2025 defined a large chargeability anomaly directly below Mt Dillon that may indicate sulphide minerals within a preserved intrusive system. A follow-up IP section placed the chargeable response about 200 to 300 metres below surface, with a deeper resistivity anomaly that could mark pervasive hydrothermal alteration in a porphyry system.

Two holes are planned, sharing a collar location but drilled at different azimuths to test the anomaly from separate angles. Proposed depths are 575 metres and 700 metres. The drilling is expected to take four to six weeks, with core logging, photography and sampling to follow.

Great Southern interprets the alteration, metal depletion, and preserved topographic high at Mt Dillon as characteristics consistent with a leached lithocap above a potentially large intrusive system. The mapped mineral assemblage is consistent with a high-temperature, low-pH hydrothermal system. Lower ground around the Mt Dillon outlier contains strong clay-pyrite-silica alteration and pyrite sulphides that make up 3% to 10% of the rock.

Planned future exploration at Edinburgh Park includes further IP surveying, a ground gravity survey, and continued surface geochemical sampling and mapping. Great Southern expects the program to generate further targets beyond Mt Dillon as work progresses through 2026 and 2027.

Gold Fields’ Alpha Score sits at 65 on AlphaScala’s proprietary scale, a Moderate reading that reflects the company’s positioning in the current gold environment. The major’s involvement in the Mt Dillon project signals continued appetite for early-stage exploration in Queensland’s gold belts.

Drilling results are expected in the second half of the year, with each hole taking roughly two to three weeks to complete.

Related: Gold Fields stock page | Gold profile