Sunstone Metals (ASX:STM) found a "significant" gold-copper porphyry at its Bramaderos project in Ecuador, according to a Tuesday filing with the Australian bourse.

Trench sampling from the discovery, named Copete, confirmed surface porphyry gold-copper mineralization, yielding 113 meters at 0.64 grams per tonne of gold-equivalent, within 214 meters at 0.5 grams per tonne of gold-equivalent, the filing said.

The discovery expands the Bramaderos mineralized cluster, indicating potential for extensive open pit operations, according to the filing.

Sunstone's shares rallied 14% in afternoon trade.