Sunstone Metals Extends Bramaderos Mineralisation with 200m Drill Intersect

Strong Mineralised Intersections Extend Bramaderos Footprint

Sunstone Metals Ltd (ASX:STM) has reported robust assay results from its ongoing drilling campaign at the Bramaderos Gold-Copper Project in southern Ecuador. The third and fourth holes at the Copete-Porotillo porphyry complex have intersected wide mineralised intervals of 200m and 148m respectively, both grading approximately 0.40 g/t gold equivalent (AuEq). These results substantially extend the known mineralisation beyond the existing 3.6 million ounce AuEq resource, reinforcing Sunstone’s ambition to convert a significant portion of its 1.7 to 3.5 million ounce Exploration Target into defined Mineral Resources.

The ongoing 26-hole, 5,000m diamond drilling program has completed 12 holes to date, with more assay results pending. The Copete and Porotillo systems lie adjacent to each other, with geological interpretations suggesting possible connectivity at depth. The recent holes, drilled on orthogonal azimuths, confirm mineralisation continuity over a 300m by 200m block trending northeast-southwest. Higher-grade sub-intervals within these holes, including 43.7m at 0.58 g/t AuEq and 59.1m at 0.47 g/t AuEq, highlight the potential for economically meaningful zones within the broader mineralised envelope.

Exploration Target Conversion Underpins Resource Growth Strategy

Sunstone’s Managing Director Patrick Duffy emphasised the strategic significance of these results, stating they support the company’s plan to grow the Bramaderos resource by progressively upgrading the large exploration target. The Copete-Porotillo complex hosts an Exploration Target of 135–180 million tonnes at 0.40–0.60 g/t AuEq, representing 1.7 to 3.5 million ounces AuEq, which remains conceptual pending further drilling and evaluation. The new drilling campaign aims to delineate this target into a resource, potentially rivaling the adjacent Brama-Alba-Melonal system that currently hosts the 3.6 million ounce resource.

These developments build on earlier strong drilling results from the first two holes in the program, which intersected 200m at 0.45 g/t AuEq and 162m at 0.32 g/t AuEq respectively. The program’s rapid progress and consistent assay grades indicate a robust mineralised system with substantial lateral and vertical continuity. The potential resource expansion could have significant economic implications, enhancing mine life, production profiles, and cash flow forecasts, as outlined in the recent Bramaderos Scoping Study that projected a 23-year mine life and US$0.9 billion NPV.

Porotillo Drilling Targets Deeper Magnetic Body

At Porotillo, seven holes have been completed with two more underway, focusing initially on establishing a shallow resource to around 200m depth. Drilling has encountered high-level intrusive breccia bodies forming a carapace over a large magnetic target identified by 3D inversion modelling. This underlying magnetic body corresponds closely with surface mineralisation and represents a priority target for deeper drilling once initial assay results are received. The phased approach aims to define both near-surface mineralisation and the potentially larger, deeper porphyry system.

Sunstone’s approach reflects a methodical progression from surface sampling and trenching, which previously identified extensive mineralised zones, to targeted diamond drilling designed to convert exploration potential into economic resources. The company’s strong infrastructure position and community engagement underpin its development strategy in Ecuador’s Loja Province.

Exploration and Funding Outlook

While the Bramaderos project currently boasts a 3.6 million ounce gold-equivalent resource, the broader porphyry systems at Bramaderos and the nearby El Palmar project contain Exploration Targets of multi-million ounce scale, underscoring the region’s potential as a long-life gold-copper mining centre. Sunstone continues to evaluate funding options to advance these projects, balancing resource growth with development studies and strategic opportunities within Ecuador’s mining sector.

Drilling results remain subject to ongoing assay confirmations and geological interpretation, with true widths of mineralisation yet to be established. The company’s next steps include completing the current drill program, updating resource estimates, and advancing feasibility studies, all contingent on securing appropriate funding. The evolving exploration narrative at Bramaderos will be critical to watch as Sunstone seeks to unlock value from one of Ecuador’s most promising gold-copper assets, following a series of encouraging milestones including the wide gold-copper zones reported in April.