Sunstone Metals Ltd (ASX:STM) has discovered gold-copper porphyry at its Bramaderos project in southern Ecuador, meaning mineralisation at the play is now spread across an area of 2 kilometres by 1.8 kilometres, suggesting a large open-pit project is possible.

The discovery was made through trench sampling at the Copetegold-copper porphyry target, which confirmed significant mineralisation of this type at surface.

This included 113 metres at 0.64 grams per tonne (g/t) gold-equivalent (0.51g/t gold, 0.07% copper, and 1.2g/t silver) in trench ML-01, within 214.0 metres at 0.50g/t gold equivalent (0.37g/t gold, 0.08% copper, and 1.1g/t silver).

Sunstone has predicted that the red metal is leached at surface, and that drilling is likely to pick up higher grades.

The discovery holds particular significance for the Bramaderos porphyry exploration target – estimated as being between 3.3 and 8.6 million ounces – suggesting scope for it to be increased.

Managing director Patrick Duffy said he expected more positive news from the project in the future.

“The Copete porphyry is another exciting new discovery that adds to the large-scale potential at Bramaderos, and we don’t expect it to be the last,” he said.

“Copete is located next to the 2.7Moz AuEq2 Brama-Alba Resource and the large Melonal exploration target, which further highlights the potential scale of the opportunity at Bramaderos.

“Taken together, it reinforces that Bramaderos is a world-class multi-decade mining opportunity and increases the Project’s value to third parties looking for hard-to-find gold and copper projects with genuine scale.”

Sunstone has been trading at 0.7 cents.

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