Sunstone Metals (ASX: STM) has reported a significant 462-meter surface trench intersection at its Porotillo prospect, expanding mineralisation and reinforcing the Bramaderos exploration target.
The recent trenching results from Porotillo highlight a substantial intersection, with trench PO-5 returning 462.22m at 0.55 g/t AuEq, comprising 0.36 g/t gold, 0.11% copper, and 1.43 g/t silver.
Within this broad intersection, higher-grade sub-intervals included 194.90m at 0.67 g/t AuEq (0.46 g/t gold, 0.12% copper, 1.96 g/t silver) and 153.02m at 0.60 g/t AuEq (0.38 g/t gold, 0.13% copper, 1.31 g/t silver).
This significant find at Porotillo remains open on all sides, confirming the continuity of gold-copper-silver mineralisation.
Earlier trenching results from Porotillo had also indicated promising grades, with one reporting 29m at 0.91 g/t AuEq and another 22m at 1.19 g/t AuEq.
Bramaderos Target Bolstered
The latest results from Porotillo serve to enhance the conceptual Bramaderos target, which is estimated at 135–180 million tonnes (Mt) grading between 0.25–0.40 g/t AuEq, for a total of 1.7–3.5 million ounces AuEq.
This exploration target is distinct from the established Bramaderos Mineral Resource, which, as of the November 2025 Mineral Resource Estimate, stands at 220 Mt at 0.50 g/t AuEq for a total of 3.6 Moz AuEq.
The potential for additional resources at Porotillo adds to the overall prospectivity of the Bramaderos project.
The Bramaderos Concession is part of a joint venture, with Sunstone Metals holding an 87.5% ownership interest.
The remaining 12.5% is held by SolGold, with their share loan carried.
Drilling and Scoping Study Advance
To accelerate resource definition, a second drill rig is arriving on site.
This additional capacity will support ongoing drilling efforts at the Copete-Porotillo area.
The primary aim is to convert the identified exploration targets into JORC-compliant resources.
Drilling is already progressing at Copete-Porotillo, with the company also evaluating other exploration targets within the extensive Bramaderos concession.
Complementing the exploration activities, metallurgical testwork and mining scoping activities are currently underway.
These studies are crucial for supporting the project's economic assessment and de-risking future development.
Context of Project Development
Sunstone Metals has been actively progressing its Bramaderos project, successfully raising $8 million in December 2025 through a share placement.
These funds were specifically allocated to advance the Bramaderos Scoping Study and to accelerate the drilling programmes.
Further corporate activity saw a 30-for-1 share consolidation proposed in January 2026, intended to simplify the capital structure and enhance the company's appeal to a broader investor base while supporting ongoing capital management.
Previous exploration efforts in February 2026 had already highlighted the discovery of high-grade surface mineralisation at Porotillo.
These earlier findings strongly supported the potential for expanding the Bramaderos resource base.
Outlook and Risks
Sunstone Metals' latest surface results from Porotillo significantly expand the known mineralisation and bolster the Bramaderos Exploration Target.
With drilling intensifying and a scoping study advancing, the company is positioned for potential resource growth.
However, investors should remain aware of inherent risks.
Funding constraints could potentially impact the pace of drilling and the completion of the scoping study, while there is also exploration risk involved in converting conceptual targets into mineable resources.
Furthermore, the execution risk associated with ambitious exploration and development programmes needs careful management.
Future developments will also be influenced by commodity price fluctuations.
