Sunstone Metals continues to expand its Bramaderos gold-copper resource in Ecuador, with recent drilling at Porotillo delivering long, consistent mineralised intersections outside the existing 3.6Moz resource. The company aims to upgrade a significant exploration target to a JORC resource later this year.
- All 12 holes assayed return wide gold-copper intervals
- Porotillo holes PTDD006 and PTDD007 hit 200m and 151m mineralisation
- Drilling extends mineralisation footprint by 380m southeast
- Trenching program underway to complement drilling and resource update
- Exploration target of 1.7 to 3.5Moz AuEq targeted for resource conversion
Porotillo Drilling Delivers Consistent, Wide Gold-Copper Zones
Sunstone Metals Ltd (ASX:STM) has reported another strong batch of drilling results from its Bramaderos gold-copper project in southern Ecuador, reinforcing the potential for substantial resource growth. The latest assays from two holes at the Porotillo prospect, PTDD006 and PTDD007, returned 200 metres at 0.62 g/t AuEq and 151 metres at 0.54 g/t AuEq respectively, both from surface. These wide intervals include higher-grade sections, with PTDD006 hitting 19 metres at 1.01 g/t AuEq and PTDD007 delivering 26 metres at 0.84 g/t AuEq.
These holes lie on the same long-section as the previously reported PTDD004 hole and extend the gold-copper mineralisation footprint southeast by 380 metres, bringing the total mineralised length on this section to 480 metres. This continuity underscores the predictable nature of the Bramaderos porphyry system and supports Sunstone's strategy to significantly expand the current 3.6Moz mineral resource.
Resource Growth Strategy Focuses on Porotillo-Copete Exploration Target
Sunstone’s ongoing 5,000-metre diamond drilling campaign across Porotillo, Copete, and Melonal prospects has now completed assays for 12 holes, all returning long mineralised intersections. Porotillo, adjacent to the pit-constrained Bramaderos resource, is a key focus area where the company is targeting conversion of a large exploration target, estimated at 135 to 180 million tonnes grading between 0.40 and 0.60 g/t AuEq, translating to 1.7 to 3.5 million ounces of gold equivalent, into a JORC-compliant resource later in 2026.
Complementing the drilling, an extensive trenching program is underway at Porotillo to improve surface definition of mineralisation. This approach, combining sub-horizontal trench sampling with vertical drilling, aims to provide a robust dataset for the planned resource update in the second half of the year. The trenching program also targets extensions beyond the current drill grid, enhancing the understanding of mineralisation continuity and grade distribution.
Geological Setting and Mineralisation Characteristics
The mineralisation at Porotillo is hosted within intrusion breccias exhibiting strong magnetite alteration and multiple generations of porphyry quartz veins. Copper sulphides such as chalcopyrite and chalcocite dominate, accompanied by minor molybdenite and zinc sulphides. The drilling has delineated a mineralised footprint extending 575 metres northwest-southeast and up to 180 metres across northeast-southwest, with ongoing assays from additional holes expected to further define this zone.
Sunstone’s Managing Director Patrick Duffy highlighted that the geometry of mineralisation is taking shape as drilling and trenching data converge, revealing a continuous mineralised domain that appears to represent a major centre within the Bramaderos property. He expressed confidence that the current phase of exploration will significantly expand the resource base, derisking the project and enhancing its value.
Bramaderos Project Overview and Broader Exploration Potential
The Bramaderos project currently holds a mineral resource estimate of 220 million tonnes at 0.50 g/t AuEq for 3.6 million ounces of gold equivalent, predominantly in the indicated and inferred categories. Beyond the delineated resource, Sunstone has identified multiple exploration targets, including the Porotillo-Copete complex and the Melonal system, which remain conceptual but promising.
Sunstone is advancing a scoping study that confirms project viability and substantial growth potential. The company also operates the El Palmar project in northern Ecuador, which hosts a 64 million tonne resource at 0.60 g/t AuEq for 1.2 million ounces AuEq and carries a significant exploration target of 15 to 45 million ounces AuEq. Both projects benefit from solid infrastructure and strong community engagement, factors critical for eventual development.
Next Steps and Market Implications
With assays pending from seven additional drill holes at Porotillo, the market can expect further updates that may refine the resource expansion narrative. The planned resource upgrade in the second half of 2026 will be a key catalyst, as it will incorporate the latest drilling and trenching data to better quantify the size and grade of the expanded mineralised zones. Sunstone’s ongoing strategic efforts to secure funding and advance project studies suggest a sustained focus on unlocking value in Ecuador’s underexplored gold-copper belt.
Bottom Line?
Sunstone’s latest drilling at Bramaderos strengthens the case for a significant resource upgrade, but pending assays and the conversion of exploration targets to resources remain critical milestones to watch.
Questions in the middle?
- Will the pending assay results confirm further extensions of high-grade mineralisation at Porotillo?
- How will Sunstone’s funding strategy evolve to support the resource upgrade and project development?
- What impact could the Bramaderos expansion have on Ecuador’s gold-copper mining landscape?