Great Southern Mining Limited (ASX:GSN) released its Quarterly Activities Report for the period ending 31 March 2026 on 21 April 2026, outlining material progress at its flagship Duketon Gold Project in Western Australia. The quarter was dominated by assay results from a 5,234m reverse circulation (RC) drilling program at the Golden Boulder discovery, which extended gold mineralisation over a strike length of approximately 3.5km. The results confirm the scale potential of the Main Line shear zone and support the case for a maiden JORC Mineral Resource estimate in the northern portion of the prospect.

Operationally, GSN commenced its first deep diamond drilling at Golden Boulder in March 2026 under a co-funded Western Australian Government Exploration Incentive Scheme (EIS) grant, with two holes completed and core processing underway. A further EIS-supported diamond hole was drilled at the Diorite Hill Layered Intrusive Complex within the East Laverton Project, targeting reef-style PGE-nickel-copper mineralisation, with assays pending. At the corporate level, GSN closed the quarter with A$5.6 million cash and announced a A$4.2 million placement, plus an additional A$0.4 million from directors subject to shareholder approval.

For investors, the March 2026 quarterly positions GSN as a well-funded gold explorer with a scalable primary target and optionality across gold, PGE, nickel and copper. The combination of drill-ready targets, government co-funding, and a strengthening treasury creates a setup where news flow over the June 2026 quarter — particularly from diamond drill assays and a possible maiden resource — is likely to remain the key share price driver.

Key Facts

  • Company: Great Southern Mining Limited
  • ASX Ticker: GSN
  • Announcement Date: 21 April 2026
  • Reporting Period: Quarter ended 31 March 2026
  • Strike Extension: Gold mineralisation now defined over approximately 3.5km at Golden Boulder
  • Drilling Completed: 5,234m RC program (56 holes) in late 2025; deep diamond drilling commenced March 2026
  • Key Intercepts: 6m at 6.7 g/t Au from 48m including 1m at 34.5 g/t Au (25GBRC054); 5m at 5.1 g/t Au including 1m at 23.9 g/t Au (25GBRC030)
  • Government Support: Up to A$220,000 WA EIS co-funding secured for two diamond holes at Golden Boulder
  • Placement: A$4.2 million equity raising announced; additional A$0.4 million from directors (subject to shareholder approval)
  • Cash Position: A$5.6 million at 31 March 2026

Announcement Overview

The quarterly report provides a consolidated update on exploration, corporate and capital activities for the three months to 31 March 2026. Its central narrative is the maturation of the Golden Boulder discovery, located within GSN's 100%-owned Duketon Gold Project in the highly productive Duketon Greenstone Belt. Assay results from the late-2025 RC program were received in January 2026 and significantly extended the mineralised footprint along strike, with every drill line crossing the prospective shear zone returning significant gold intercepts.

The report also documents the commencement of deep diamond drilling at Golden Boulder in March 2026, a step-change in exploration intensity designed to test the down-dip continuity of mineralisation beneath historic shallow workings. The program is co-funded under the WA Government's Exploration Incentive Scheme, which reduces direct capital exposure for GSN shareholders. A separate EIS-funded deep diamond hole at the Diorite Hill target within the East Laverton Project is testing reef-style PGE-Ni-Cu mineralisation — adding polymetallic exposure to the portfolio.

Company Background

Great Southern Mining Limited is an ASX-listed gold and base metals exploration company headquartered in Balcatta, Western Australia. Its flagship asset is the 100%-owned Duketon Gold Project, consisting of granted exploration licences totalling 549 km² in the Duketon Greenstone Belt, located north of Laverton. The belt is shared with ASX-listed gold producer Regis Resources Limited (ASX: RRL), which has defined in excess of 10 million ounces of gold mineral resources across its tenure. GSN interprets three primary mineralised corridors as continuing into its tenements, including approximately 8km of the Erlistoun Trend, 7km of the Garden Well Trend and 11km of the Rosemont to Ben Hur Trend.

GSN also holds the East Laverton Project (100%), which includes the Diorite Hill Layered Intrusive Complex, and the Mt Dillon IP target in Queensland, where drilling is scheduled to commence in the June 2026 quarter following the cessation of the northern Queensland wet season. The Company's strategy is to deliver greenfield discoveries in proven mineral provinces, leveraging modern geophysics and government co-funding to de-risk drilling.

Detailed Analysis

Golden Boulder: From Prospect to Emerging Camp

Golden Boulder sits on a prominent north-south structural trend that hosts multiple Regis Resources gold deposits, including Rosemont (>2 Moz), Baneygo (~380 Koz) and Ben Hur (~390 Koz). Historical production between 1900 and 1955 at Golden Boulder is recorded at 1,915 tonnes at 28.6 g/t Au for 1,761 ounces. The late-2025 RC program had three objectives — infill and extension in the north, southern extensional drilling, and first-pass drilling along the southern 1.3km — and all three were achieved.

Headline intercepts include 6m at 6.7 g/t Au from 48m (with 1m at 34.5 g/t Au) in 25GBRC054, and 5m at 5.1 g/t Au from 25m (including 1m at 23.9 g/t Au) in 25GBRC030. Multiple drill holes returned intercepts exceeding 5 g/t Au over 1–2 metres, pointing to a robust high-grade vein system hosted within a broader, lower-grade shear envelope. The 3.5km strike length is now comparable in scale to mid-tier undeveloped gold prospects in the region, although resource definition drilling is still required to convert mineralisation into a JORC-compliant estimate.

Deep Diamond Drilling and EIS Co-Funding

The March 2026 commencement of deep diamond drilling is strategically important. Golden Boulder's structural setting — on or near interpreted first-order mantle-tapping shear zones — is consistent with the settings of the region's major gold deposits. Testing depth extensions is a logical next step, particularly given historic drilling rarely exceeded 20m. EIS co-funding of up to A$220,000 for two diamond holes at Ogilvies reduces GSN's cash burn and signals government confidence in the project's regional prospectivity.

Corporate and Capital Markets Activity

GSN closed the quarter with A$5.6 million in cash and announced a A$4.2 million equity placement, with directors and management committing an additional A$0.4 million subject to shareholder approval. Insider participation is a meaningful signal of alignment and suggests management views the current share price as a constructive entry point ahead of key catalysts.

Strategic Significance

The strategic significance of the March 2026 quarter is three-fold. First, the strike extension at Golden Boulder materially expands the potential resource footprint and re-rates the asset from a high-grade exploration target to an emerging camp-scale opportunity. Second, the involvement of the WA Government through EIS grants de-risks capital-intensive diamond drilling. Third, the addition of working capital through the placement ensures GSN has funding for multiple drill programs across WA and Queensland without near-term dilution pressure beyond the placement itself.

Market & Investor Impact

Micro-cap gold explorers are typically driven by discovery momentum and drill-ready catalysts. GSN's March 2026 quarterly report delivers both: the 3.5km strike extension is a measurable data point that informs resource potential, and the commencement of deep diamond drilling provides a clear near-term catalyst. Investors should, however, weigh these positives against the speculative nature of pre-resource exploration and the capital market context for small-cap mining placements, where share price performance can be volatile around raises.

What This Means for Investors

Investors holding or considering GSN should track four specific milestones over the coming quarters: (1) assay results from the initial Golden Boulder diamond hole (completed to 652m); (2) Diorite Hill PGE-Ni-Cu assay results; (3) the commencement of drilling at the Mt Dillon IP target in Queensland; and (4) any timeline for a maiden Golden Boulder JORC resource estimate. A positive outcome from any of these milestones could drive a re-rating, while weaker-than-expected assays or delays could test market patience.

Risks and Opportunities

Risks

  • Exploration risk: significant intercepts do not guarantee economic mineralisation.
  • Funding risk: further capital raises may be required if drill programs expand.
  • Commodity risk: gold price movements materially affect project economics.
  • Regulatory and permitting risk associated with WA exploration tenure.

Opportunities

  • Maiden JORC Mineral Resource at Golden Boulder could unlock a step-change re-rating.
  • Multi-commodity exposure (Au, PGE, Ni, Cu) reduces reliance on a single commodity cycle.
  • Proximity to Regis Resources' +10 Moz endowment provides geological and M&A optionality.
  • Strong insider alignment through director participation in the placement.

Key Takeaways

  • Golden Boulder gold mineralisation now extends over approximately 3.5km of strike.
  • Deep diamond drilling at Golden Boulder and Diorite Hill commenced during the quarter.
  • A$4.2m placement plus A$0.4m director participation strengthens the balance sheet.
  • Cash at 31 March 2026 stood at A$5.6 million.
  • Drilling at Mt Dillon (Queensland) is expected to commence in the June 2026 quarter.

Bottom Line

The March 2026 quarter consolidates Great Southern Mining's position as a credible junior gold explorer with scale, funding and meaningful near-term catalysts. While exploration risk remains, the 3.5km strike at Golden Boulder, combined with EIS-supported deep diamond drilling and a strengthening balance sheet, gives GSN a tangible platform for resource definition and value creation through the remainder of 2026.

Disclaimer

This article is based solely on the corresponding ASX announcement and is for informational purposes only. It does not constitute financial, investment, legal, or tax advice. Investors should conduct their own due diligence and consult a licensed financial adviser before making investment decisions. Past performance is not indicative of future results.