Sunstone Metals Ltd (ASX:STM) has calculated its maiden mineral resource estimate (MRE) for the El Palmar gold-copper porphyry project in northern Ecuador and the results establish a foundation for a large-scale Tier-1 discovery.
This first resource estimate is a reported 1.2 million ounces of gold equivalent (AuEq) from the T1 deposit, a strong starting point for further exploration.
The T1 deposit also enjoys the advantage of being a surface-level resource, making it amenable to open-pit mining.
Sunstone managing director Patrick Duffy said: “These results confirm that El Palmar is a major discovery with clear potential to host a Tier-1-scale inventory with an exploration target of 15 million ounces to 45 million ounces gold equivalent that is complemented by the maiden mineral resource.
Joining ‘globally significant’ club
“El Palmar is in the same belt as Solgold’s +3-billion-tonne Cascabel Alpala deposit and Codelco’s neighbouring +1-billion-tonne Llurimagua deposit and we fully expect the project to become a member of this globally significant Tier 1 deposit club.”
The initial pit-constrained MRE is based on the T1 gold-copper porphyry deposit, which contains 64 million tonnes of ore grading 0.60 g/t AuEq. This includes 0.41 g/t gold, 0.13% copper and 0.7 g/t silver, calculated at a cut-off grade of 0.4 g/t AuEq.
The MRE is derived from 17,699 metres of drilling, indicating a robust platform for the future expansion of the resource.
The company is further buoyed by an initial exploration target of 1.0 to 1.2 billion tonnes at grades ranging from 0.3 g/t to 0.7 g/t gold and 0.1% to 0.3% copper.
This represents a significant potential discovery, with estimates of 10 to 27 million ounces of contained gold and 1 to 3.7 million tonnes of copper.
The conceptual exploration target is based on just three of the many deposits within the El Palmar project, which suggests there is significant upside potential.
Favourable recovery rates
Early-stage metallurgical testing indicates favourable recovery rates, with combined flotation and leach methods achieving 90% gold recovery and 78% copper recovery.
Further optimisation studies are planned to improve these recovery rates.
The El Palmar project is within the same geological belt as some of Ecuador’s most prominent porphyry deposits, including Solgold’s Cascabel Alpala deposit and Codelco’s Llurimagua deposit.
Sunstone’s ongoing exploration will focus on expanding the MRE and exploration target as drilling continues.
With gold prices at record highs above A$4,000 per ounce and strong fundamentals for copper, Sunstone is advancing discussions with potential strategic partners to unlock the full value of El Palmar.
World-class gold-copper
These results underscore the project’s potential to become a world-class gold-copper discovery, aligning it with other major deposits in the region.
“It is rewarding to be in a position to articulate just how important El Palmar is as a discovery. We are confident that ongoing drilling will continue to grow the size of both the mineral resource and exploration target,” Duffy continued.
“With the resource and exploration target at El Palmar on the table, gold at record prices above A$4,000/ounce and the fundamentals for copper being incredibly strong, we look forward to advancing our discussions with strategic partners who have the capacity to help us unlock the full value of our discoveries in a timely manner.”