Sunstone Metals is pushing the boundaries of its Bramaderos gold-copper project in Ecuador, with all 20 holes assayed in the current drilling campaign delivering long mineralised intersections. The Porotillo porphyry system alone now extends mineralisation over an area of roughly 500m by 200m beyond the existing 3.6Moz resource.
- All 20 drill holes return significant gold-copper intersections
- Porotillo mineralisation footprint expanded beyond current resource
- Strongest hole PTDD012 hits 213m at 0.53 g/t AuEq from surface
- Trenching underway to support resource upgrade in H2 2026
- Exploration Target of 1.7 to 3.5 Moz AuEq targeted for conversion
Drilling Extends Bramaderos Mineralisation Footprint
Sunstone Metals Ltd (ASX:STM) continues to build momentum at its Bramaderos gold-copper project in southern Ecuador, with the latest assays confirming the expansion of known mineralisation beyond the existing 3.6 million ounce (Moz) resource. The current drilling program, focused on the Porotillo, Copete, and Melonal prospects, has delivered long and consistent gold-copper intersections in all 20 holes assayed to date.
The standout result comes from hole PTDD012, which returned an impressive 213.35 metres grading 0.53 grams per tonne gold equivalent (AuEq), including a higher-grade 52-metre interval at 0.76 g/t AuEq starting just 11 metres from surface. Such thick mineralised intercepts underline the scale and continuity of the porphyry system at Porotillo, which now covers an area of approximately 500 metres by 200 metres outside the current resource boundary.
Consistent High-Quality Intersections Across Multiple Holes
The recent tranche of eight holes at Porotillo (PTDD008 to PTDD015) all returned robust mineralised intervals, with several holes exceeding 150 metres in length. For example, PTDD009 intersected 297.8 metres at 0.40 g/t AuEq, including 55.25 metres at 0.62 g/t AuEq, while PTDD013 delivered 200.89 metres at 0.43 g/t AuEq with a 34-metre sub-interval at 0.84 g/t AuEq.
These results build on earlier drilling successes at Bramaderos, reinforcing the project's potential to significantly grow its resource base. The mineralisation is characterised by disseminated and vein-hosted gold and copper within quartz diorite intrusions and breccia bodies, with copper occurring in multiple mineral forms including chalcopyrite and chalcocite. Notably, copper grades tend to be higher near surface due to supergene enrichment processes.
Trenching and Metallurgical Work to Support Resource Upgrade
Complementing the drilling, a trenching program is underway at Porotillo aimed at expanding the mineralisation footprint to the northeast and southwest. Several trenches have been excavated and sampled, with assays pending for the latest trenches. This surface data, combined with drilling results, will feed into a planned resource estimate update scheduled for the second half of 2026.
Sunstone has also initiated metallurgical testwork on drill core samples to better understand the processing characteristics of the ore. Preliminary studies indicate a two-stage recovery process involving flotation and cyanide leaching, with estimated recoveries of 86% for copper and 89% for gold.
Targeting Conversion of Large Exploration Target
The current drilling campaign is designed to convert a significant portion of the Bramaderos Exploration Target, estimated at 135 to 180 million tonnes grading 0.40 to 0.60 g/t AuEq for 1.7 to 3.5 Moz AuEq, into a JORC-compliant Mineral Resource. While the Exploration Target remains conceptual, the consistent mineralised intersections provide encouraging evidence for resource growth.
Managing Director Patrick Duffy emphasised the project's momentum: “With every drill hole intersecting additional mineralisation, we are increasing the project's scale, enhancing its value, and further demonstrating its significant growth potential.”
Broader Project Strategy and Outlook
Beyond Bramaderos, Sunstone also holds the El Palmar project in northern Ecuador, featuring a 1.2 Moz AuEq resource and a substantial exploration target. Both projects benefit from excellent infrastructure and community support, underpinning the company's long-term vision to develop multi-decade gold-copper mining centres.
Sunstone is concurrently evaluating funding options to accelerate exploration and development activities, following a recent $10 million capital raise that bolstered its cash position. The company plans further drilling at Bramaderos and El Palmar over the next two years, subject to funding availability.
Bottom Line?
Sunstone’s latest drilling results at Bramaderos solidify its position to upgrade a major exploration target, but the path to resource conversion hinges on upcoming assay results, trenching data, and metallurgical outcomes.
Questions in the middle?
- Will the upcoming resource upgrade confirm the conversion of the large Exploration Target to a JORC Resource?
- How will metallurgical testwork results influence the project's economic viability and processing strategy?
- What funding model will Sunstone adopt to sustain its aggressive drilling and development plans over the next two years?