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16 April 2025

Great Southern Copper plc

("GSC" or the "Company")

Scout RC Drilling at Viuda Confirms Potential for Mineralised Porphyry Style Au-Ag-Cu System

Diamond drilling to commence at Viuda Negra targeting porphyry Au-Ag-Cu style vein system with assays up to 4.2 g/t Au, 145 g/t Ag, and 0.56 % Cu in outcrop.

Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold exploration in Chile, is pleased to report the results of scout reverse circulation ("RC") drilling and ground exploration activities at its Viuda Prospect, part of GSC's extensive Especularita Project, Chile.

Highlights:

·   Seven initial scout RC holes drilled for 1,020 m confirm a broad-scale porphyry alteration system with zoned geochemistry and trace element trends consistent with porphyry type deposits

·    Hole RC005 returned 12m at 1.5 g/t Au and 0.47% Cu from 132m, including 2m at 4.4 g/t Au and 0.94 % Cu from 136m

·  Results indicate increasing widths and grades of metal Au-Cu-Ag and trace-element Mo-Bi-Sb-Se geochemistry to the south coincident with quartz-pyrite (±chalcopyrite) veining and breccia hosted in pervasive alteration characteristic of porphyry Au (±Cu) deposits

·    Diamond drilling to commence targeting porphyry Au style sheeted quartz veins discovered at new Viuda Negra prospect with grades up to 4.2 g/t Au, 145 g/t Ag and 0.56 % Cu in outcrop

·    Phase II diamond drilling at Mostaza completed with 16 holes drilled for total of 1,701.7m

·    Company holds options to own 100% of Viuda and Viuda Negra

·    Project located in coastal metallogenic belt with excellent access and infrastructure

Sam Garrett, Chief Executive Officer of Great Southern Copper, said: "The Phase II drilling programme at Mostaza is now complete. Whilst we begin the detailed work of evaluating all the drill results to this stage the proposed metallurgical test work and detailed exploration along trend will continue.

"Exploration across the broader Especularita portfolio has also been continuing with a diamond drilling rig now mobilising to our new Viuda Negra prospect to test exciting gold, copper and silver anomalies identified in recent soil and rock chip sampling programmes. Viuda is located 20 kilometres to the southwest of the high-grade copper-silver mineralisation at Mostaza and represents a different style of target, namely large-scale, porphyry type gold, silver and copper mineralisation.

"Evaluation of results from our recent scout RC drilling programme at Viuda has successfully confirmed the type of alteration and associated zonation patterns of metals and trace elements that is characteristic of porphyry type deposits. Analysis of trace-element vector patterns suggests that widths and grades of mineralisation is potentially increasing toward the south. In addition, follow-up of multi-element soil anomalies has led to the discovery of a new gold-silver prospect at Viuda Negra with outcrop samples grading up to 4.2 g/t gold and 145 g/t silver.

"With gold prices currently at all-time highs, the gold-silver rich Maricunga-style porphyry gold and copper vein alteration evident in outcrop at Viuda represents a very exciting target for GSC."

Viuda prospect

The Viuda prospect, located approximately 20km to the southwest of the Company's Cerro Negro prospect (Figure 1), is part of GSC's Especularita Project comprising 18km² of concessions centred upon a prominent hill of resistive silicified rock (Chingay Hill) and surrounded by a large (2km diameter) bowl-shaped depression ("bajo") - a geological setting typical of many porphyry deposits¹ (Figure 1) formed by supergene weathering and oxidation of the dominantly albite-pyrite-clay altered volcanics and intrusive rocks. The zoned, clay-rich alteration also produces a distinctive colour anomaly in spectral imagery².

Figure 1. Location of the Viuda Project, Especularita (left) and Geological map of Viuda and Viuda Negra prospects showing main features and location of inset maps (right). The roughly circular zone of albite-pyrite-clay alteration coincides well with satellite imagery and soil geochemistry.

Results of scout RC Drilling

Broad-spaced, reconnaissance scout RC drilling at Viuda was designed to improve geological understanding of the project and provide metal and trace-element geochemistry with the aim to see beneath the leached, supergene-altered surface and vector future exploration efforts toward potential centres of porphyry type mineralisation³. A total of seven holes were completed, initially surrounding the central Chingay Hill area, for a total of 1,020m (Figure 2).

Drillholes VIU25-RC001, 002, 003 and 006 were drilled as a fence across the northern side of the Chingay Hill where north-south trending corridors of mineralisation were previously mapped (Figure 3). The drillholes intercepted strongly pyrite-albite-clay altered volcanic and intrusive rocks with up to 10% disseminated pyrite with broad zones (>5-50m) of anomalous silver (>0.1 g/t Ag) including localised zones of quartz-sulphide veinlets grading up to 8m at 0.19% Cu (VIU25-RC003).

Drillholes VIU25-RC004, 005 and 007 were drilled to the South of Chingay Hill testing the southern extension of the mapped corridors (Figure 3). VIU25-RC004 intercepted anomalous silver (>0.1 g/t Ag) plus pathfinder trace elements Mo, Bi, As, Sb and Se across the entire drillhole, with quartz-sulphide veinlets and breccias associated with intermediate and advanced argillic alteration grading up to 2m at 0.33% Cu.

VIU25-RC005 was drilled 200m south of RC004 and intercepted zones of quartz-sulphide veinlets associated with magnetite-albite-chlorite and pyrite-albite-clay alteration grading up to 12m at 1.5 g/t Au and 0.47% Cu including individual samples up to 4.39 g/t Au and 0.94% Cu. Silver, together with pathfinder elements Mo, Bi, Sb and Se were also anomalous along the entire drillhole and at higher grades than other drillholes.

Preliminary analysis of results indicate that alteration intensity and mineralised intervals and grades for Cu-Ag-Mo-Sb-Bi-Se are increasing to the south, suggesting that the potential for higher grades may continue in this direction. Further work, including detailed mapping, geophysics and additional scout drilling is being planned.

 Figure 2. Viuda Project, Drill Location Map showing the location of scout RC drillholes and interpreted corridors of quartz-sulphide veinlets and breccia in red.  Geochem vector trends indicate the system is improving toward the south.

Figure 3. Viuda Project: Geological sections for Viuda scout holes showing interpreted zones of quartz-sulphide veining with relevant assay result intercepts of anomalous Cu-Au plus Ag and trace elements indicative of porphyry type mineralisation. 

Viuda Negra Prospect:

Follow-up mapping of the soil geochemistry results from a project-wide survey has discovered outcropping sheeted and stockworked banded-quartz veins at Viuda Negra, located 1km to the northeast of Changay Hill, that are typical of Au-rich porphyry systems. Subsequent channel chip sampling across the outcrops has returned assays up to 1m at 4.2 g/t Au and 0.12% Cu (Figure 4). Nearby several epithermal-style ledges were also discovered with intense multi-stage quartz veinlet stockworks associated with advanced argillic alteration. Rock chip sampling of several of the ledges returned values up to 145 g/t Ag and 0.56% Cu (see Figure 5).

Scout diamond drilling is planned, and a drill rig has been mobilised, to test the outcropping ridges of anomalous gold and silver mineralisation at Viuda Negra. Up to 4 drill holes are proposed for a total of up to 400 - 500m.

Figure 4: Geology and recent rock chip geochemistry results for Viuda Negra prospect, Viuda.

Figure 5: Viuda Negra: Left -sheeted quartz veins at Cruachan Hill with rock chip assay results up to 4.2 g/t Au and 0.12% Cu. Right - Advanced argillic altered HS style "Ledge" at Scarlett Ridge with up to 29.9 g/t Ag. Similar rocks also yield up to 145 g/t Ag.

References:

1. RNS 2087I (15 Oct 2024); New Cu-Au exploration target identified at Viuda.

2. RNS 7037M (19 Nov 2024); Exploration results define Viuda drilling targets.

3. RNS 4525N (25 Nov 2024): Drilling commences at Viuda prospect, Especularita.

Enquiries:

Notes for Editors:

About Great Southern Copper

Great Southern Copper PLC is a UK-listed mineral exploration company focused on the discovery of copper-gold deposits in Chile. The Company has the option to acquire rights to 100% of two projects in the under-explored coastal belt of Chile that are prospective for large scale copper-gold deposits. Chile is a globally significant mining jurisdiction being the world's largest copper producer.

The two, early-stage Cu-Au projects comprise the Especularita and San Lorenzo Projects, both located in the coastal metallogenic belt of Chile which hosts significant copper mines and deposits, including Teck's Carmen de Andacollo copper mine, and boasts excellent access to infrastructure such as roads, power and ports. Significant historical small-scale and artisanal workings for both copper and gold are readily evident in both exploration project areas.

Great Southern Copper is strategically positioned to support the global market for copper- a critical battery metal in the clean energy transition around the world. The Company is actively engaged in exploration and evaluation work programmes targeting both large tonnage, low to medium grade Cu-Au as well as high-grade Cu-Ag-Au deposits.

Further information on the Company is available on the Company's website: https://gscplc.com

Competent Person Statement  

The information in this announcement that relates to exploration results is based on and fairly represents information reviewed or compiled by Mr Sam Garrett, a Competent Person who is a Member of the Australian Institute of Geoscientists and a Fellow of the Society of Economic Geologists. Mr Garrett is the CEO and a shareholder of Great Southern Copper PLC. Mr Garrett has sufficient experience that is relevant to the styles of mineralisation and types of deposit under consideration and to the activity being undertaken to qualify as a Competent Person as defined in the 2012 Edition of the "Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves". Mr Garrett has provided his prior written consent to the inclusion in this announcement of the matters based on information in the form and context in which it appears.

This announcement includes information that relates to Exploration Results prepared and first disclosed under the JORC Code (2012) and extracted from the Company's previous LSE announcements as noted, and the Company's Prospectus dated 20 December 2021. Copies of these announcements are available from the LSE Announcements page of the Company's website: www.gscplc.com.

The Company confirms that it is not aware of any new information or data that materially affects the information included within the Prospectus dated 20 December 2021.

Forward Looking and Cautionary Statements

Some statements in this announcement regarding estimates or future events are forward-looking statements. They include indications of, and guidance on, future earnings, cash flow, costs and financial performance. Forward-looking statements include, but are not limited to, statements preceded by words such as "planned", "expected", "projected", "estimated", "may", "scheduled", "intends", "anticipates", "believes", "potential", "predict", "foresee", "proposed", "aim", "target", "opportunity", "could", "nominal", "conceptual" and similar expressions. Forward-looking statements, opinions and estimates included in this report are based on assumptions and contingencies which are subject to change without notice, as are statements about market and industry trends, which are based on interpretations of current market conditions. Forward-looking statements are provided as a general guide only and should not be relied on as a guarantee of future performance. Forward-looking statements may be affected by a range of variables that could cause actual results to differ from estimated or anticipated results and may cause the Company's actual performance and financial results in future periods to materially differ from any projections of future performance or results expressed or implied by such forward-looking statements. So, there can be no assurance that actual outcomes will not materially differ from these forward-looking statements.