Great Southern Copper plc (LSE: GSCU) has reported "exceptional" assay results from its Phase I drilling program at the Mostaza Mine, part of the Cerro Negro project in Chile, confirming significant high-grade copper-silver mineralization that remains open in all directions.
The latest results from holes CNG25 DD002-DD005 demonstrate continuity of the high-grade mineralization previously reported in hole CNG25 DD001, which intersected 20m @ 3.31% Cu and 270g/t Ag from 27m depth, including a higher-grade zone of 7m @ 5.72% Cu and 490g/t Ag from 31m.
"These outstanding results confirm that high-grade Cu-Ag mineralisation is continuing to depth and along strike and demonstrate that the former Mostaza mine has the potential to be a high-grade, high-value Cu-Ag deposit," said Sam Garrett, Chief Executive Officer of Great Southern Copper.
The company noted that assay grades from the current drilling program are consistently and significantly higher than those reported in historical drill programs at the site, suggesting previous resource estimates may have understated the deposit's potential.
Phase II Drilling Program Underway
Following these encouraging results, Great Southern Copper has commenced Phase II drilling at Mostaza with two diamond drill rigs mobilized to the site on March 10. The expanded program represents a significant escalation of exploration activity at Cerro Negro.
One rig is positioned within the Mostaza mine pit area to test for depth and strike extensions to the known mineralization intersected by Phase I drillholes. The second rig is located approximately 500m along strike to the south, where it will test new exploration targets below and around Lens 4, an area where limited historical drilling reportedly failed to reach the intended target mineralization.
"We have entered a very exciting phase of exploration at Cerro Negro and have a lot of work to do as we progress to demonstrate the potential economic viability of this exciting deposit," Garrett added.
Initial plans call for approximately 1,000-1,500m of drilling, with additional drilling contingent upon results. The company is also preparing to extend the drilling timeframe beyond the current permit, which allows for drilling until April of this year.
Strategic Importance and Next Steps
The Phase II drilling program is designed to expand the historical resource area on a semi-regular grid pattern that could, if results warrant, allow progression to a new JORC resource estimate. Results will also contribute to the commencement of metallurgical and geotechnical studies.
The Mostaza prospect is strategically located at low elevation with excellent access to infrastructure and mining services in Chile, a globally significant mining jurisdiction and the world's largest copper producer. The coastal metallogenic belt where the project is located hosts significant copper mines and deposits, including Teck's Carmen de Andacollo copper mine.
Great Southern Copper holds an option to acquire 100% ownership of the Mostaza mine and the broader Cerro Negro project, positioning the company to support the growing global demand for copper—a critical battery metal in the clean energy transition.
Assay results for the remaining Phase I drill holes (CNG25 DD006-009) are currently pending at ALS Laboratories, with further updates expected as the Phase II program progresses.
"This programme represents a significant escalation of activity at Cerro Negro," said Garrett. "Besides continuing to deliver important information regarding the geology of the Mostaza deposit, the results for this drilling will also contribute to the commencement of metallurgical and geotechnical studies."
