Replacement: Drilling Commences at Viuda Negra

The following amendment has been made to the "Scout Diamond Drilling Commences at Viuda Negra Prospect, Viuda" announcement released on 23/04/2025 at 07:17 under RNS No 8279F

Correcting the figure "45g/t Ag" on the third bullet point in the Highlights section to "145g/t Ag"

All other details remain unchanged.

The full amended text is shown below.

THIS 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.

23 April 2025

Great Southern Copper plc

("GSC" or the "Company")

Scout Diamond Drilling Commences at Viuda Negra Prospect, Viuda

Targeting epithermal-porphyry style Au-Ag-Cu mineralisation

Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold exploration in Chile, is pleased to announce that drilling has commenced on its Viuda Negra prospect located within the Especularita project.

Highlights:

· Scout diamond drilling commences at Viuda Negra prospect targeting Au-Ag-Cu mineralisation

· Initial programme comprises 2 - 4 scout holes for a total of up to 500m

· Drilling targeting outcropping porphyry-epithermal style alteration with rock chip samples assaying up to 4.2g/t Au, 145g/t Ag and 0.56% Cu1

· GSC holds options to own 100% of the Viuda and Viuda Negra prospect

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

Sam Garrett, CEO for Great Southern Copper in Chile, said: "We are excited to commence scout drilling at the Viuda Negra prospect where recent exploration by GSC has identified outcropping evidence of epithermal-porphyry type mineralisation with assay grades in rock chips and channel chip samples ranging up to 4.2g/t Au, 145g/t Ag and 0.56% Cu.

"The style of gold-rich sheeted veining outcropping at Viuda Negra and elsewhere across the Viuda prospect, is characteristic of Maricunga type porphyry gold deposits in Chile. Significantly, this style of gold deposit has not previously been recognised in the coastal belt of Chile.

"The Viuda and Viuda Negra targets emphasise the exciting depth of the Especularita drilling pipe-line which is further enhanced by the current environment of record gold and silver prices. The location and scale of the Especularita project coupled with the deposit style and commodity optionality on offer remains a key differentiating factor for GSC."

Viuda Negra Prospect:

Follow-up mapping of anomalous soil geochemistry results at Viuda has discovered outcropping sheeted and stockworked, banded quartz-magnetite veins at Viuda Negra, located 1km to the northeast of Changay Hill (Figure 1), that are characteristic of Au-rich porphyry systems in Chile. Subsequent channel chip sampling across the outcrops has returned assays up to 1m at 4.2 g/t Au and 0.12% Cu1. Nearby several epithermal-style ledges were also discovered with intense multi-stage quartz veinlet stockworks associated with epithermal type advanced argillic alteration. Rock chip sampling of several of the ledges returned values up to 145 g/t Ag and 0.56% Cu1 (Figure 2).

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Figure 1. Location of the Viuda Negra prospect, Viuda project, Especularita (left) and Geological map of Viuda and Viuda Negra prospects (right). The roughly circular zone of albite-pyrite-clay alteration coincides well with satellite imagery and soil geochemistry.

Figure 2: Geology and recent rock chip geochemistry results for Viuda Negra prospect, Viuda.

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Drilling:

Scout diamond drilling has commenced at Viuda Negra to test the outcropping ridges of anomalous gold and silver mineralisation identified by surface mapping and sampling. Up to 4 drill holes are proposed for a total of up to 400 - 500m.

Hole VNE25-DD001 is currently at 70m depth and testing sheeted, Maricunga style quartz-magnetite vein alteration at Cruachan Ridge where channel sampling has returned assay grades up to 4.2g/t Au and 0.12% Cu (Figure 2). The hole has intersected zones of quartz fracture-veining and hydrothermal brecciation (Figure 3). Hole VNE25-DD002 is planned to test epithermal style alteration outcropping at Scarlett Ridge with anomalous silver grades up to 29.9g/t Ag (Figure 2).

Figure 3: Drill core from VNE25-DD001 demonstrating Maricunga-style quartz fracture-veining (l) and hydothermal brecciation (r).

References:

1. RNS 2553F (16 April 2025): Results for scout RC drilling at Viuda

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 producer and exporter of copper.

The two, early-stage Cu-Au projects comprise 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. The coastal belt offers deposit type optionality for copper including porphyry and IOCG style deposits as well as newly recognised intrusive-related copper and gold deposits.

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.