Great Southern Copper plc (LON: GSCU), the Company focused on copper-gold-silver exploration in Chile, announces its results for the six months ended 30 September 2025 (“the Period”).
HIGHLIGHTS
Especularita Project
Cerro Negro
· Assay results released at the start of the Period for the Company’s maiden Phase I drilling programme at the Mostaza mine demonstrate the high-grade nature of the Mostaza system, with highest reported assay grades of 16.15% copper (“Cu”) and 646 grammes per tonne (“g/t”) silver (“Ag”), with four samples reporting copper assay grades over 8.0% Cu. Other standout intercepts included 33 metres (“m”) at 1.96% Cu and 60.6 g/t Ag and 9.67% Cu & 175 g/t Ag from 116.4m.
· In conjunction with the drilling, ground exploration work extended the potential mineralised strike of the Mostaza mineralised system by a further two kilometres (“km”) south of the historic Mostaza mine defining the “Mostaza Fault Zone”, with new breccia-hosted mineralisation, altered volcanic units and additional artisanal workings identified.
· Geophysical surveys were conducted across the Mostaza Fault Zone, targeting deeper extensions of the high-grade lenses and defining priority drill targets. These surveys were undertaken to assist in targeting Phase III exploration drilling at Cerro Negro up to two kilometres south of the Mostaza mine (“Mostaza”) where Phase I drilling intersected significant Cu-Ag mineralisation.
o The survey identified an IP anomaly consistent with the high-grade sulphide mineralisation drilled beneath the Mostaza mine, confirming the potential for sulphide mineralisation along trend south of the mine.
· Phase II diamond drilling delivered further encouraging results across the full programme, including intercepts of 13.9m at 1.74% Cu and 153 g/t Ag, 5m at 3.04% Cu and 322.4 g/t Ag with highest assay grades up to 10.4% Cu and 672g/t Ag. The campaign confirmed manto-style mineralisation beneath leached outcropping lenses, extended Lens 2 along strike and at depth, defined multiple new drill targets for Phase III in combination with geophysics, and confirmed a new mineralised lens (“Lens 1”) north of the main Lens 2 body.
· Phase III diamond drilling commenced with the first rig arriving at site in August. This programme is designed to extend the high-grade copper-silver mineralisation intersected in Phases I and II, test beneath shallow leached zones where drilling ended in strong silver grades, and then to step out along the Mostaza Fault trend to drill priority geochemical and geophysical targets to the south.
· Post-period on 14 October, results of the Company’s channel rock chip sampling programme at the Monolith Cu-Ag prospect (“Monolith”) identified a new 50m-wide zone of Ag-Cu mineralisation, with assays grades up to 271 g/t Ag and 2.05% Cu.
· Post-period on 14 October, the Company reported that a second diamond drill rig had arrived on site to advance Mostaza Phase III drill programme, targeting extensions and in-fill to the Lens 2 mineralisation.
· Post-period on 11 November, the Company announced it had mobilised a third drill rig to commence scout reverse circulation (“RC”) drilling. This drilling programme comprises up to 2,000m of RC drilling and is designed to test the Mostaza Fault Zone and newly identified oxide copper mineralisation in the hanging wall volcanics, where recent rock chip samples returned grades up to 2.56% Cu and 293 g/t Ag.
Viuda Negra
· Results of an initial seven-hole scout RC drilling campaign at Viuda were announced at the start of the Period, which confirmed a broad-scale porphyry type alteration system with zoned geochemistry and trace element trends consistent with porphyry type deposits, inclusing notable assay results of 12m at 1.5 g/t gold (“Au”) and 0.47% Cu.
· Scout diamond drilling at Viuda Negra commenced during the period with four drill holes completed for a total of 553 m. Drilling targeted surface alteration and Ag-Au rock geochemistry anomalies with all holes intersecting broad zones of quartz-magnetite banded veining and breccia hosted mineralisation in feldspar porphyry.
· Assay results from the diamond drilling programme confirmed the discovery of a porphyry gold mineralised system with broad mineralised intervals, including 121.5m at 0.11 g/t Au and 0.05% Cu. This system is measured at 1.2km by 0.8 km and is open, with planning underway for further exploration.
Corporate
· Post-period on 20 November, the Company successfully raised £2.5 million through a private placing with existing and new investors. This funding will be used to finance its ongoing exploration programmes at the Especularita Project in Chile.
Sam Garrett, Chief Executive Officer of Great Southern Copper, said: “This has been another strong Period for Great Southern Copper, with our exploration programmes delivering excellent progress and results across the Especularita Project. The continued success at Cerro Negro, where high-grade copper and silver mineralisation has now been intersected over an expanding footprint, reinforces our confidence in the potential scale of this system.
“We are also encouraged by the confirmation of a new porphyry gold system at Viuda Negra, which adds meaningful depth to our exploration portfolio and highlights the broader potential of Especularita to host multiple mineralised centres.
“With Phase III drilling now underway at Cerro Negro, supported by an expanded multi-rig programme and our financial position strengthened following the recent fundraise, we are well positioned for the next stage of work across our key targets. We look forward to maintaining the momentum of this Period as we work to unlock the full potential of our assets.”
Enquiries:
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Great Southern Copper plc |
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Sam Garrett, Chief Executive Officer |
+44 (0)20 4582 3500 |
