Announcement • May 23
Great Southern Copper plc Commences Geophysics Amt Survey At La Colorada Great Southern Copper plc commenced an audio-frequency magneto-telluric (AMT) geophysics survey across the La Colorada lithocap prospect at its Especularita Project. Survey to cover an area of approximately 33 km2 comprising western half of the La Colorada lithocap. Targeting large-scale porphyry copper deposits at depth below the high sulphidation lithocap. Survey to be completed in two weeks with results expected within 4-6 weeks. Results to assist with target vectoring for first-pass scout drilling of the lithocap. GSC holds rights to own 100% of the Especularita Project. Project located at low elevation with excellent access to infrastructure and mining services, and is along trend of major copper deposits including Los Pelambres, Altar and El Pachon. The La Colorada lithocap comprises the cornerstone of the Company's flagship Especularita project located 100 km south of the port of Coquimbo. The Especularita project is situated at low altitude within the Cretaceous-age coastal metallogenic belt, within a northwest-southeast trending structural lineament that links the project with notable large-scale porphyry Cu-Au mines and projects, including Los Pelambres, Altar and El Pachon. GSC's Especularita project is located at low altitude within the coastal metallogenic belt of northern Chile and within 50km radius of over 50 million tonnes of contained copper metal defined in mines and advanced projects. The Company has contracted Chile-based Southernrock Geophysics S.A. to undertake an AMT survey covering an area of approximately 33 km2 and comprising the western half of the La Colorada lithocap. The survey is planned on 500 metres grid centres and is designed to identify potential large-scale porphyry copper centres hidden at depth beneath the high-sulphidation alteration blanket. The survey parameters allow for the depth of investigation to exceed 1,000m below surface, subject to the resistivity nature of the rock. Approximate AMT survey area for the La Colorada lithocap, Especularita. Field team measuring EM activity on site at La Colorada - note the highly oxidised and clay-rich lithocap rocks in the background. Audio-frequency magneto-tellurics (AMT) is a passive electromagnetic geophysical technique ideally suited for mapping deeply buried porphyry copper deposits as it effectively penetrates thick, conductive cover (such as volcanic lithocaps) to delineate the deep, localized resistive intrusions and conductive alteration halos characteristic of porphyry systems. The method measures natural electromagnetic (EM) fields on the Earth's surface generated from lighting (high frequency) and solar winds (low frequency) to map subsurface electrical resistivity. By analyzing how these waves interact with different rock types, geophysicists can interpret geological units, fault zones, and potential mineral deposits down to depths of up to a few kilometers. Porphyry copper deposits may have distinct three-dimensional electrical signatures. When integrated through 3D inversion modelling, AMT maps these contrasts at depths ranging from 100 meters to over 2 kilometers. The causative porphyry intrusions typically appear as highly resistive bodies whereas the highly mineralized potassic cores and surrounding phyllic (pyrite-rich) and argillic alteration zones form conductive anomalies due to interconnected sulfide minerals and clay alteration. Scout RC drilling is currently in progress at the Artemisa North target with 3 holes completed for 414m. The fourth hole ART26-RC008 is currently in progress at a depth of 220m. Samples for holes ART26-RC005 and RC006 have been delivered to ALS Laboratories in Santiago by GSC personnel. Once completed at Artemisa North, the scout RC drilling programme will progress to test the Artemisa South and Victoria targets. Exploration work, including mapping and sampling, is in progress at both the Cerro Negro and Viuda prospects in preparation for drilling. Metallurgical studies are also underway for Mostaza core samples from Phases I and II of the drilling at Cerro Negro. Announcement • May 14
Great Southern Copper plc Commences Scout Rc Drilling At Artemisa North Porphyry Copper Target Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold-silver exploration in Chile, announced that scout RC drilling has commenced on the Artemisa North porphyry copper target at the Especularita Project, while drilling recently completed at the nearby Piedras Blancas target has confirmed evidence of a strong porphyry copper-style alteration system. Scout reverse circulation ("RC") drilling commences at Artemisa North porphyry copper prospect at the western margin of the La Colorada lithocap. Four holes planned to target interpreted phyllic alteration system plus test beneath historical copper workings. Rock chip geochemistry results from mine workings grade up to 1.21% Cu, 0.6g/t Au and 201ppm Mo. Large-footprint system open under shallow cover to the north and east. No previous drilling of the target. GSC holds rights to own 100% of the Artemisa North target. Prospect located at low elevation with excellent access to infrastructure and mining services and along trend of major copper deposits including Los Pelambres, Altar and El Pachon. Scout RC drilling completed at Piedras Blancas prospect with four holes drilled for 574 metres ("m"). All holes successfully intersected strong porphyry type phyllic alteration with holes PBL26 RC001 and RC002 transitioning at depth to potassic alteration including 5-15% sulphide mineralisation. Style and intensity of alteration provides proof-of-concept confirmation of a porphyry copper type setting at Piedras Blancas intersected at shallower depths than expected and further increasing prospectivity of the broader La Colorada lithocap. Samples for all four holes at Piedras Blancas have been despatched to ALS Laboratories. GSC holds rights to own 100% of the Piedras Blancas target. The Artemisa North prospect is located 1.5km south of the Piedras Blancas1 prospect on the western margin of the extensive La Colorada lithocap that comprises the Company's principal porphyry copper target within its flagship Especularita project. Mapping and sampling at Artemisa North has defined a broad zone (>1 km2) of quartz-sericite-pyrite "phyllic" alteration and stockworking confirmed by ASD spectrography. The phyllic alteration zones upwards to quartz-alunite "advanced argillic" alteration on the surrounding hilltops that is interpreted to represent a distal remnant of the La Colorada lithocap alteration. Despite intense oxidation and leaching, rock chip and soil samples define local anomalies in Cu and Mo, and abundant green and black Cu-oxides are observed in historical artisanal mines exposed on the western and eastern margins of the phyllic zone. The alteration zone remains open under shallow cover to the east towards the La Colorada lithocap, and to the north where it is interpreted to merge with the Piedras Blancas alteration zone. Drilling at the Piedras Blancas target has been completed with four scout RC holes drilled for a total of 574m. All holes intersected strong pervasive quartz-sericite-pyrite alteration providing proof-of-concept evidence for porphyry copper type phyllic alteration to depths of up to 120m from surface. The phyllic alteration comprises up to 5 - 10% disseminated and veinlet hosted pyrite mineralisation. Holes RC001 and RC002 transitioned at depth into biotite-altered "potassic" alteration with 5 - 15% disseminated and veinlet hosted pyrite, traces of chalcopyrite and quartz veinlets. The style and intensity of alteration and mineralisation identified in holes PBL26 RC001 and 002, in particular the potassic alteration, confirm that a porphyry copper type setting has been identified at Piedras Blancas at depths shallower than expected. These results further confirm and enhance the potential of the La Colorada lithocap to host one or more porphyry copper type systems at reasonable depths from surface. Further work will now focus on vectoring to the possible copper-rich core of the systems. Scout reverse circulation (RC) drilling recently commenced at Artemisa North with a view to test the prospect for evidence of porphyry copper-gold mineralisation and to provide vectors towards targets beneath the undrilled Colorada lithocap. A preliminary test comprising up to 1000m of drilling in at least four scout RC holes is now underway to assess the alteration and mineralisation. The RC drilling method employed at Especularita collects samples on two-metre intervals. Representative samples for each sample of the cuttings are collected in large, individually numbered plastic bags, which are then weighed and transferred to a riffle splitter where they are separated (or split), and homogenised, three times into two duplicate samples of approximately 5kg each. GSC personnel then ticket and label one of the ±5kg samples using preprinted ticket books. Finally, standard reference materials (SRM's or Standards), blanks, and duplicate samples are inserted into the sample sequence for the purpose of quality assurance /quality control (QAQC). The second ±5kg sample is used for geological description and stored for reference. An additional reference selection of cuttings for each two-metre sample is also retained in labelled boxes as a record of the geology of the drill hole. At the completion of each hole, the representative 5kg samples are transported as a batch from the field and delivered by Company employees to ALS Laboratories in Santago or La Serena where they are prepared for analysis (weighed, dried, crushed and pulverised). A subsequent 200g split of each sample pulp is then forwarded to the ALS geochemical laboratory in Lima, Peru, where samples are assayed for gold (30g fire assay with ICP-AES finish, ALS code AU-ICP21) and 48 major, base and trace elements by ICP-MS following a four-acid digest (ALS code ME-MS61). RC drilling was selected for this initial proof-of-concept stage as it is faster and cheaper than diamond drilling and allows for the rapid testing of more targets for the same cost. Following the completion of the Artemisa North scout RC drilling programme, the rig will proceed to the Artemisa South and Victoria prospects to complete similar drill tests targeting porphyry-related copper mineralisation. Final results are awaited for Mostaza metallurgical test work conducted on Phase I and II high-grade core samples. Planning and permitting for Phase IV drilling at Mostaza are in progress. Geophysics surveys are being planned for both the Cerro Negro prospect (extension of 2025 IP survey) and the La Colorada lithocap (AMT), anticipated to commence in May 2026. Detailed prospect-scale mapping and sampling are continuing at the Viuda and Cerro Negro prospects. New results from this ongoing work, together with results of the planned geophysics surveys, will direct targeting for the next phase of drilling at both Cerro Negro and Viuda. Announcement • Apr 20
Great Southern Copper plc Commences Drilling on Porphyry Copper Targets Great Southern Copper plc commenced scout RC drilling at the Piedras Blancas (White Stones) prospect located on the western margin of the La Colorada lithocap, in the Especularita project. Drilling to test porphyry Cu target at Piedras Blancas with initial three scout reverse circulation holes. Holes targeting silica-sericite-pyrite altered rocks with overprinting silica-pyrite stockwork alteration indicative of porphyry copper-related phyllic alteration zone. Target outcrops over 1km in diameter but extends under gravel cover to east and south. Anomalous molybdenum up to 49 ppm Mo in rock chips from leached alteration zone. Drilling aims to vector follow-up drilling toward potential potassic copper-rich porphyry zones. No evidence of historical drilling at Piedras Blancas. GSC holds the rights to own 100% of the Piedras Blancas prospect. Prospect located at low elevation with excellent access to infrastructure and mining services and along trend of major copper deposits, including Los Pelambres, Altar and El Pachon. Piedras Blancas is located at the northwestern margin of the La Colorada lithocap that comprises the Company's principal porphyry copper target within its flagship Especularita project. The Especularita project is located at low altitude within the Cretaceous-age coastal metallogenic belt, within a northwest-southeast trending structural lineament that links the project with notable large-scale porphyry Cu-Au mines and projects, including Los Pelambres, Altar and El Pachon. GSC's Especularita project is located at low altitude within the coastal metallogenic belt of northern Chile and within 50km radius of over 50Mt of contained copper metal defined in mines and advanced projects. Scout RC drilling has commenced at Piedras Blancas (White Stones), where the overlying La Colorada lithocap is interpreted to have been eroded away, exposing possible porphyry-style phyllic alteration comprising intense quartz-sericite-pyrite overprinted by stockworks and crackle veinlets of quartz-pyrite mineralisation. Intense weathering and oxidation of the surface rocks have resulted in depleted (leached) copper signatures for rock chip samples in the area. However, molybdenum, which is a useful pathfinder element for porphyry copper mineralisation, is less mobile in the oxide environment and exhibits strong anomalism with assay results up to 49ppm Mo from 13 rock samples of the alteration zone. The drilling target is further defined by a prominent broad zone of de-magnetisation in the drone magnetics survey which is a feature consistent with pervasive magnetite-destructive phyllic alteration in porphyry copper settings. On a local prospect scale, however, subtle magnetic features are evident which will be tested with this drilling programme. An initial test of three scout RC drill holes has been designed with the aim of determining the depth of oxidation and leaching and confirming that the alteration observed in outcrop corresponds at depth to the phyllic zone of a porphyry copper system. The inner phyllic zone, or shell, may host lower grade copper mineralisation, however, the results for this drilling are aimed to provide strong vector indicators for possible follow-up drilling targeting the potassic core of the porphyry system which typically comprises higher copper grades and may be located at depth or laterally beneath the gravel cover (or both). Oxidised quartz-sericite-pyrite (QSP) alteration overprinted by quartz-pyrite stockwork veining exposed in outcrop at Piedras Blancas (White Stones) prospect, Especularita. Alteration is characteristic of the phyllic alteration zone in porphyry copper systems. Following the completion of the Piedras Blancas scout RC drilling programme, the rig will proceed to the Artemisa and Victoria prospects to complete similar drill tests targeting porphyry-related copper mineralisation. Final results for Phase III diamond drilling at Mostaza are still awaited, as are results for metallurgical testwork conducted on Phase I and II high-grade core samples. Planning and permitting for Phase IV drilling at Mostaza are in progress. Geophysics surveys are being planned for both the Cerro Negro prospect (extension of 2025 IP survey) and the La Colorada lithocap (AMT), anticipated to commence in May 2026. Detailed prospect-scale mapping and sampling are continuing at the Viuda prospect. New results from this ongoing work, together with results of the recent ground magnetic survey, will direct targeting for the next phase of drilling at Viuda. Preliminary plan for scout RC drilling at Piedras Blancas illustrating geology and Vertical Signal Magnetic Intensity. 
