REG - Great Southrn.Copper - Drill Results Extend Mineralisation at Cerro Negro

Great Southern CopperAnnouncement

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RNS Number : 6736X  Great Southern Copper PLC  23 March 2026

 

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 March 2026

 

Great Southern Copper plc

("GSC" or the "Company")

 

Scout RC Drilling Results Extend Mineralisation 1.5km along strike at Cerro
Negro

 

High-grade silver-base metal mineralisation intersected in all holes

 

Great Southern Copper plc (LSE: GSCU), the company focused on
copper-gold-silver exploration in Chile, is pleased to announce latest results
for the scout RC holes of its Phase III drilling campaign at Cerro Negro, part
of the Especularita Project.

 

Highlights:

·    High-grade Ag-Cu+Pb-Zn intersected in all RC holes with silver grades
up to 105 g/t Ag

·    Results extend strike of mineralisation up to 1.5km south of Mostaza
mine and open

·    New Ag-Pb-Zn lenses discovered at depth, associated with targeted IP
chargeability anomalies, including;

o  RC041:  26m @ 62.8 g/t Ag, 0.43% Zn and 0.19% Pb from 200m, including

§ 12m @ 101.8 g/t Ag, 0.70% Zn and 0.28% Pb from 204m

·    Near-surface Ag-Pb mineralisation confirms leached upper zone of the
system:

o  RC040: 16m @ 32.9 g/t Ag and 0.19% Pb from 24m, including

§ 8m @ 56.2 g/t Ag and 0.24% Pb from 26m

·    New Cu-Ag zone intersected in hanging wall volcanics, defines a
high-priority near-surface target:

o  RC048:  6m @ 0.72% Cu and 78.27 g/t Ag from 24m, including

§ 2m @ 1.04% Cu and 86 g/t Ag from 24m

·    Strong correlation between mineralisation and IP chargeability
anomalies, confirming effectiveness of geophysical targeting

·    Planning in progress for Phase IV resource and exploration drilling

·    Significant exploration targets at Monolith and southern Mostaza
extension remain untested

·    GSC holds option to own 100% of the Cerro Negro prospect, including
the Mostaza mine

·      Prospect located at low elevation with excellent access to
infrastructure and mining services

 

Sam Garrett, Chief Executive Officer of Great Southern Copper, said: "These
important scout RC drill results have been highly successful in demonstrating
that high-grade silver-base metal mineralisation extends at least 1.5
kilometres south of the Mostaza mine consistent with surface geology and
geochemistry anomalies as well as IP chargeability anomalies along the Mostaza
Fault Zone. These anomalies extend a further 1km to the south and remain
untested by drilling emphasising the increasing scale potential of the Cerro
Negro system.

 

Geological investigation and interpretation of the RC chips is on-going,
however, the identification of multiple stacked and zoned lenses of
silver-base metal continues to strengthen our geological model and reinforces
similarities to the high-grade system discovered at Mostaza.

 

A significant outcome of these results includes the strong correlation between
mineralisation and IP chargeability anomalies which now provides us with a
highly effective exploration tool to delineate and prioritise future drill
targets along this emerging mineralised corridor.

 

With multiple high-priority targets now defined, we are well positioned to
advance these areas through follow-up drilling in Phase IV.  Additionally,
our team is currently mapping and sampling further along the Mostaza Fault
Zone to the south as well as the Monolith Zone as we continue to unlock the
broader district-scale potential of Cerro Negro."

 

 

 

Figure 1: Location map of the Especularita Project, Chile. The project is
located at low elevation within the coastal metallogenic belt and along trend
of significant mines and projects in development.

Phase III Scout RC Drilling Results - Central Mostaza Fault Zone:

 

Scout RC drilling was designed to test geochemical and geophysical targets
located approximately 1-1.5km south of the Mostaza mine along the Mostaza
Fault Zone (MFZ), where previous mapping, geochemistry and geophysics have
defined a prospective mineralised corridor extending over several kilometres
(Figure 2).

 

Figure 2: Mostaza Fault Zone (MFZ) highlighting location of Phase III Scout RC
Drilling relative to gradient array IP chargeability and rock chip
geochemistry for silver (Ag g/t).

 

 

RC039, 040, 041 & 044:

 

Drilling targeted a deep IP chargeability anomaly coincident with an
outcropping lens of highly leached, silicified breccia where surface sampling
returned grades up to 86.4 g/t Ag(1). Drilling intersected two distinct zones
of silica-sulphide breccia mineralisation initially interpreted to be
shallowly dipping toward the west (Figure 3).

 

An upper, shallow Ag-Pb zone correlates with the outcropping silicified
breccia and a weak near-surface chargeability anomaly. The shallow
mineralisation is interpreted to represent the oxidised and leached upper
portions of the mineralised system, analogous to near-surface zones observed
at Mostaza where copper depletion is common. Significant intercepts for the
shallow mineralisation include;

 

·    RC040: 16m @ 32.9 g/t Ag and 0.19% Pb from 24m, including

o  8m @ 56.2 g/t Ag and 0.24% Pb from 26m

 

·    RC039:   6m @ 6.9 g/t Ag and 0.25% Pb from 18m within highly
leached material

 

A second, more strongly mineralised Ag-Pb-Zn zone was intersected at depth and
correlates with a stronger IP chargeability anomaly (Figure 3) with
significant intercepts including;

 

·      RC041:   26m @ 62.8 g/t Ag, 0.43% Zn and 0.19% Pb from 200m,
including

o  12m @ 101.8 g/t Ag, 0.70% Zn and 0.28% Pb from 204m

 

·      RC044: anomalous Ag-Zn-Pb mineralisation up to 11.6 g/t Ag, 0.12%
Zn and 0.07% Pb

 

These results support the Company's emerging geological model of multiple
stacked west-dipping lenses, consistent with observations at Mostaza where
multiple lenses form within a structurally controlled system.

 

The metal zonation observed between lenses suggests a complex and evolving
mineralising system, with distinct lenses characterised by variable sulphide
assemblages ranging from high-grade Cu-Ag through to Pb-Zn dominant and mixed
Pb-Zn-Cu-Ag mineralisation. This variability, both between and potentially
within lenses, is potentially indicative of a large and dynamic hydrothermal
system. Ongoing interpretation is focused on identifying vectors within this
zonation to better target higher-grade mineralisation.

 

The strong correlation between the Ag-Pb-Zn mineralised zones and IP
chargeability anomalies confirms the effectiveness of geophysical targeting
and provides a robust tool for identifying and prioritising drill targets.

 

 

 

Figure 3: Cross Section showing RC holes 039, 040, 041 and 044 with assay
results and IP chargeability

 

 

 

RC047 & 048:

 

A further 200m to the south scout RC drilling also tested newly-identified
oxide copper mineralisation within the hanging wall volcanics west of the MFZ,
a target area defined by mapping and surface sampling returning grades up to
2.56% Cu and 293 g/t Ag(2).

 

RC048 intersected a zone of copper oxide and bornite mineralisation hosted in
quartz veinlets, with significant results including;

 

·      RC048:  6m @ 0.72% Cu and 78.27 g/t Ag from 24m, including

o  2m @ 1.04% Cu and 86 g/t Ag from 24m

 

RC047 intersected the interpreted up-dip extension of the same zone,
characterised by highly leached material with anomalous Cu-Ag up to 0.16% Cu
and 21.6 g/t Ag.

 

Mineralisation is partially obscured by gravel and talus cover, however,
windows of outcrop and surface geochemistry define a mineralised trend of at
least 300m in this central MFZ area, with rock chip samples returning up to
1.37% Cu and 596 g/t Ag (Figure 4). Additional high-grade samples downslope to
the west (up to 2.14% Cu and 293 g/t Ag) suggest the presence of multiple
west-dipping lenses, analogous to the stacked lens geometry observed at
Mostaza. The shallow nature of the mineralisation makes it a high priority
target for follow up drilling in phase IV.

 

Figure 4: Oblique view looking NE showing RC drilling results and surface
geochemistry.

 

This zone of outcropping oxide copper mineralisation with anomalous Cu-Ag
geochemistry is mapped for a further 1km to the south and has not been tested
by drilling.

 

 

Next steps:

 

Preparation for the next phase of drilling is at an advanced stage and the
results reported here will impact on-going drill plans potentially expanding
the proposed drilling programme.

 

Ground exploration at Monolith and the southern extention of the MFZ is
continuing with positive results also expected to impact the exploration plans
of the Phase IV drill programme.

 

Results for the metallurgical test-work being conducted on core from the
Phases I and II programmes is still progressing with results pending.

 

Elsewhere across the broader Especularita project work is progressing to
prepare for the next phase of drilling at the Viuda prospect as well as scout
drilling of the Victoria, Sauce, Megalo and Lipa prospects.

 

Note regarding Laboratory turn-around times:

Chile is experiencing a rapid increase in exploration activity, coinciding
with the summer exploration season in the high Andes (November to April) and
further compounded by rising metal prices. Consequently, sample preparation
times are significantly longer than in the past, with turnaround times of over
two months now typical for assay results.

 

The Company has implemented strategies designed to improve the turn-around
times and reduce costs including prioritising the sampling of distinct mineral
zones identified in the core and despatching these to the lab in advance of
the remainder of the holes' samples.

 

 

  References:

1.    RNS 5192G (29(th) April 2025): Exploration Results Extend Cerro Negro

2.    RNS 0337H (11(th) November 2025): Third Drill Rig Mobilising to Cerro
Negro

 

 

Engage with the GSC management team directly by asking questions, watching
video summaries and seeing what other shareholders have to say. Navigate to
our Interactive Investor hub here: https://gscplc.com/ (https://gscplc.com/)

 

 

Enquiries:

 

 Great Southern Copper plc             c/o BlytheRay
 Sam Garrett, Chief Executive Officer  +44 (0) 20 7138 3204

 SI Capital Limited
 Nick Emerson                          +44 (0) 1483 413500

 BlytheRay
 Tim Blythe / Megan Ray                +44 (0) 20 7138 3204

                                       GSC@blytheray.com

 

Subscribe to our news alert service: https://gscplc.com/auth/signup
(https://gscplc.com/auth/signup)

 

 

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-silver deposits in Chile. The Company has the
option to acquire mining rights to 100% of Especularita project in the
under-explored coastal belt of Chile that is prospective for large scale
copper-gold-silver deposits. Chile is a globally significant mining
jurisdiction being the world's largest producer and exporter of copper.

 

The Especularita Project is 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 the exploration
project area. 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 (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
(http://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.

 

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