Great Southern Copper PLC (LSE:GSCU, FRA:E9E) has started drilling at the Piedras Blancas prospect in Chile, kicking off its first drill test of a porphyry copper target at the Especularita project as it looks to vector towards a potentially higher-grade core.
The London-listed explorer said an initial three-hole scout reverse-circulation programme is underway at Piedras Blancas, on the western margin of the La Colorada lithocap.
The holes are designed to test altered rocks showing silica-sericite-pyrite and quartz-pyrite stockwork features that the company believes are consistent with the phyllic zone of a porphyry copper system.
Surface sampling has already pointed to encouraging pathfinder chemistry.
Great Southern said rock chips from the leached alteration zone returned molybdenum values of up to 49 parts per million from 13 samples, while the target area itself outcrops over more than 1 kilometre in diameter and continues beneath gravel cover to the east and south.
The company also noted there is no evidence of previous drilling at Piedras Blancas.
Chief executive Sam Garrett said the programme is aimed at getting below the oxidised surface zone to confirm the alteration at depth and help guide follow-up drilling towards the potassic, copper-richer part of any porphyry system.
The prospect sits in Chile’s coastal metallogenic belt, with Great Southern highlighting its low elevation, infrastructure access and regional setting along trend from major copper deposits including Los Pelambres, Altar and El Pachon.
Once the Piedras Blancas campaign is complete, the rig is set to move on to Artemisa and Victoria, while geophysics at Cerro Negro and La Colorada is expected to begin in May 2026.