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Phase III Drilling Completed at Cerro Negro
Great Southern Copper PLC has completed its Phase III drilling program at the Cerro Negro prospect, which included 17 diamond drillholes totaling 2,923 meters and 6 RC holes totaling 1,032 meters, extending the high-grade Cu-Ag system at Mostaza and identifying a new base metal Ag-Pb-Zn lens. Previously announced results from Lens 2 at Mostaza showed grades such as 0.69m at 9.76% Cu and 716 g/t Ag, and planning is underway for 2026 drilling across multiple targets including Mostaza, Monolith, the Mostaza Fault Zone, the Viuda prospect, and the Colorada porphyry Cu-Au system. Disclaimer*
About this update from Great Southern Copper Plc
[{"type":"text","content":"\n\n \nTHIS ANNOUNCEMENT CONTAINS INSIDE INFORMATION AS STIPULATED UNDER THE UK VERSION OF THE MARKET ABUSE REGULATION NO 596/2014 WHICH IS PART OF ENGLISH LAW BY VIRTUE OF THE EUROPEAN (WITHDRAWAL) ACT 2018, AS AMENDED. ON PUBLICATION OF THIS ANNOUNCEMENT VIA A REGULATORY INFORMATION SERVICE, THIS INFORMATION IS CONSIDERED TO BE IN THE PUBLIC DOMAIN.\n \n \n12 January 2026\n \nGreat Southern Copper plc\n(\"GSC\" or the \"Company\")\n \nPhase III Drilling Completed at Cerro Negro Extends High-Grade Cu-Ag System at Mostaza\nCompany Advances Drill Planning for 2026\nGreat Southern Copper plc (LSE: GSCU), the company focused on copper-gold-silver exploration in Chile, is pleased to announce the successful completion of its Phase III diamond and reverse circulation (\"RC\") drilling programme at the Company's flagship Cerro Negro prospect, part of the Especularita Project.\nPhase III represents the largest and most advanced drilling campaign completed by GSC to date and has continued to build upon the discovery of the high-grade copper-silver system at Mostaza and along the broader Mostaza Fault Zone (\"MFZ\") which extends over 2 km south of the mine.\nAssay results for multiple completed holes remain pending and are expected to feed directly into planning for the next phase of drilling across several high-priority targets.\nHighlights\n· Phase III programme now completed, comprising 17 diamond drillholes for 2,923 metres and 6 RC holes for 1,032 metres, with significant operational outcomes including:\no High-grade Lens 2 mineralisation at Mostaza extended to depth and along strike\no Potential for multiple \"stacked\" high-grade Cu-Ag lenses recognised at Mostaza\no New base metal Ag-Pb-Zn lens discovered at Mostaza in the Lens 2 area\no Oxide and sulphide mineralisation identified in RC drilling within the MFZ trend\n· Previously announced Phase III results1 for Lens 2 at Mostaza included:\no DD029: 0.69m @ 9.76% Cu and 716 g/t Ag from 87.93m and\no DD031: 1.1m @ 8.92% Cu and 715.3 g/t Ag from 96.5m\n· Assays pending for all RC holes and remaining diamond holes\n· Planning for next phases of drilling now underway, including additional targets id...