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.

11 March 2025

Great Southern Copper plc

("GSC" or the "Company")

Phase II Resource Drilling Commences at the Mostaza Cu-Ag Deposit, Cerro Negro

Two diamond rigs mobilised to expand resource and test exploration targets

Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold and silver exploration in Chile, is pleased to announce that Phase II drilling has commenced at its Mostaza Cu-Ag prospect, Cerro Negro.

Highlights:

·    Phase II drilling commenced at Mostaza utilising two diamond drill rigs

·    Drilling to target depth and strike extensions to high-grade Cu-Ag mineralisation following results of CNG25-DD001¹

o  20m @ 3.31% Cu and 270g/t Ag from 27m, including

o    7m @ 5.72% Cu and 490g/t Ag from 31m

·    Exploration drilling along trend south of the Mostaza pit also planned

·    Initial plans are to drill approximately 1,000-1,500m with additional drilling subject to results

·    Results for Phase II drilling to assist commencement of metallurgy and geotechnical studies

·    Core samples for Phase I drill holes CNG25002 - 009 are at ALS Laboratories with assay results pending

Sam Garrett, Chief Executive Officer of Great Southern Copper, said: "Following the exciting results delivered by the first hole of our Phase I drill programme, our team in Chile is champing at the bit to get started with the Phase II drilling at Mostaza.

"This programme represents a significant escalation of activity at Cerro Negro and aims to take maximum advantage of the Phase I drilling permit process which allowed for drilling to April of this year. Preparations to extend the drilling time-frame are also in progress.

"Besides continuing to deliver important information regarding the geology of the Mostaza deposit, the results for this drilling will also contribute to the commencement of metallurgical and geotechnical studies."

GSC Commences Phase II Drilling at Mostaza Cu-Ag mine, Cerro Negro

Two diamond drill rigs, from Chilean company R. Muñoz based in nearby La Serena, arrived on site on Monday 10 March and have commenced drilling operations including environmental and safety inspections and inductions.

One rig is positioned within the Mostaza mine pit area to test for depth and strike extensions to the known mineralisation intersected by Phase I drillholes CNG25DD001 - DD005, including CNG25DD001 which intersected 20m @ 3.31% Cu and 269.89 g/t Ag from 27m depth¹.

The purpose of this drilling is to expand the historical resource area on a semi-regular grid pattern that will, if results warrant, allow progression to a new JORC resource estimate.

The second rig is positioned approximately 500m along strike to the south where it will test new exploration targets below and around Lens 4, where limited historical drilling reportedly failed to reach the intended target mineralisation.

Results for the Phase II drilling will also be used to commence metallurgical and geotechnical studies.

References:

1.    RNS 5182Y_LSE_Cerro Negro assays return 20m @3.3% Cu & 270g/t Ag

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 and lithium 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 San Lorenzo and Especularita 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 deposits as well as high-grade Cu-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.