REG - Great Southrn.Copper - Geophysics Define New Cerro Negro Drill Targets

Great Southern CopperAnnouncement

12/08/2025 07:00

For best results when printing this announcement, please click on link below:
https://newsfile.refinitiv.com/getnewsfile/v1/story?guid=urn:newsml:reuters.com:20250812:nRSL9584Ua&default-theme=true

RNS Number : 9584U  Great Southern Copper PLC  12 August 2025

 

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.

 

 

12 August 2025

 

Great Southern Copper plc

("GSC" or the "Company")

 

Final IP Geophysical Results Define Multiple New Drill Targets at Cerro Negro

 

Results correlate strongly with geology and geochemistry defining significant
mineralised structure

 

Great Southern Copper plc (LSE: GSCU), the company focused on
copper-gold-silver exploration in Chile, is pleased to announce final results
for its pole-dipole IP ("PDIP") and audio magneto-telluric ("AMT") surveys at
the Cerro Negro project which confirm potential for a significant Cu-Ag
mineralised trend south of the Mostaza mine.

 

Highlights:

 

·    Coincident PDIP chargeability and resistivity anomalies at Mostaza
mine (Line 1) correlate strongly with high-grade Cu-Ag mineralisation
identified at depth in previous drilling

·    Results confirm structural complexity of the Mostaza deposit

·   Anomalies on Lines 2-5 are consistent with earlier reported gradient
array IP anomalies(1) and geochemistry results(2) defining a 2.5km mineralised
trend south of the Mostaza mine

·    2D inversion modelling of AMT results identifies targeted north-south
structural trend

·    Geophysical results identify priority untested targets for Phase III
drilling over 2.5km trend

·    Planning for Phase III exploration drilling advanced with expected
start date late August

·    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
exciting pole-dipole IP results clearly identify the high-grade sulphide
mineralisation drilled by GSC beneath the historical Mostaza mine, and provide
compelling targeting vectors for our upcoming drilling campaign designed to
explore the extensions of the mineralised system to the south along the
Mostaza Fault trend. Importantly, these results also confirm the
post-depositional structural complexity of this deposit and  suggest
geophysics will be a critical tool to assist with directing future drill
programmes and ultimately understanding the complex architecture of the
deposit.

 

"The geophysical anomalies confirm and correlate with earlier geochemistry and
gradient array IP results indicating potential for a mineral trend of up to
2.5km south of the Mostaza mine which remains open.

 

"These results significantly enhance the potential of the project and
represent a compelling opportunity for discovery in our upcoming Phase III
programme which we anticipate starting before the end of August, subject to
rig availability."

Pole-Dipole IP (PDIP) / Resistivity Survey Results:

 

Details of the physical parameters of the geophysics surveys, conducted by
Southern Rock Geophysics SpA, at Cerro Negro were reported previously(1)
including results of the gradient array IP survey. GSC has now completed
interpretation of the results from its pole-dipole IP / Resistivity and AMT
surveys. Line 1 was designed as a control line as it tests the known Mostaza
Cu-Ag mineralisation adjacent to the pit. Line 2 tests known mineralisation at
surface and Lines 3-5 are exploration lines(1) designed to confirm surface
exploration results and assist with follow-up exploration drill targeting.

 

The high-grade Cu-Ag mineralisation intersected in GSC's previous
drilling(3,4,5,6) at the Mostaza mine correlates closely with the upper margin
of a discrete coincident chargeability and resistivity anomaly in the 2D
inversion model for Line 1. Sulphide mineralisation zones identified in
drilling consistently occurs at the zone of highest contrast on the top side
of the anomaly (see Figure 1, 2). The Line 1 anomaly dips approximately 50°
NW, consistent with the interpreted geometry of the Cu-Ag mineralised body
intersected in diamond drilling. Moderate chargeability values, up to 15
milliseconds ("ms"), are consistent with the low total-sulphide but high-grade
assemblage of chalcocite, bornite and digenite mineralisation. The
chargeability feature is coincident with a high-resistivity anomaly (Figure 2)
in both the PDIP and AMT inversions (up to 800 ohm-metres), interpreted to
reflect silicification and late quartz vein-crackle alteration associated with
the mineralisation.

 

The Line 1 chargeability-resistivity anomaly provides a clear geophysical
signature aligned with the known Cu-Ag mineralisation drilled at Mostaza and
further provides a clear vector for targeting similar anomalies identified
both down-dip, up-dip and laterally along strike to the south on subsequent
test-lines 2 - 5.

 

The Mostaza Fault, interpreted as a potentially significant controlling
structure for mineralisation along the Cerro Negro trend, is recognised in the
geophysics on all lines as a pronounced steeply west-dipping break in both
chargeability (PDIP) and resistivity (PDIP and AMT), closely correlated with
surface mapping and drillcore observations (Figures 3, 4).

 

On Line 1, the interpreted Mostaza Fault appears to structurally dislocate the
chargeability-resistivity anomaly suggesting the anomaly to the east of the
fault has potentially represents a downthrown or is a separate, untested lens
of mineralisation. With values comparable to the drill-tested part of the
anomaly (up to 12 ms) dips approximately 50° north-west, mirroring the
geometry of the previously defined and drill-tested mineralisation (Figure 1,
2).

 

At surface, the chargeability feature potentially correlates with highly
anomalous silver and copper assays from the previously mapped Lens 5. At
surface the lens is intensely leached and oxidised, with rock chip assays up
to 86.3 g/t Ag and 0.66% Cu indicating the potential for higher grade sulphide
mineralisation at depth which is yet to be tested with drilling.

 

Audio Frequency Magneto-telluric (AMT) Results:

 

The AMT results confirm broader geologic trends with 3D inversion modelling
clearly identifying a resistive domain to the east correlating with dacitic
dome rocks in apparent faulted contact (Mostaza Fault) with low-resistive
volcanic units to the west (Figure 5). Strong silicic alteration and
silica-magnetite brecciation mapped along the fault potentially enhance the
resistive contact evident in the modelling.

 

On all the survey lines, there is a consistent shallow west-dipping contact
between an overlying wedge or layer of relatively low resistivity overlying
higher resistivities in the western part of each section. This contact, as
described for the PDIP result on Line 1, may represent a prospective location
for the development of sulphide mineralization associated with silicification
away from the perhaps structural complexity of the Mostaza Fault Zone.

 

Figure 1: Cerro Negro Prospect, Mostaza Mine: Cross section for 2D inversion
model of chargeability for PDIP Line 1. Mostaza high-grade Cu-Ag drill
intercepts coincide closely with upper margin of the chargeability anomaly
(left side of Mostaza Fault). Similar anomalies to the right side of the fault
are untested by drilling but demonstrate evidence of mineralisation at
surface.

 

Figure 2: Cerro Negro Prospect, Mostaza Mine: Cross section for 2D inversion
model of resistivity for PDIP Line 1. Resistivity and chargeability anomalies
are coincident confirming mineralisation associated with highly resistive
silicified alteration. (note: for resistivity, blue colours are high).
Similarly, the resistivity confirms structural complexity with dislocated
anomalies and potential untested anomalies upslope of the mine.

 

Figure 3: Cerro Negro Prospect, Mostaza Trend: Oblique view looking to the NE
showing the 2D inversion of PDIP chargeability for all 5 lines together with
superimposed surface geochemistry.

 

Figure 4: Cerro Negro Prospect, Mostaza Trend: Oblique view looking to the NE
showing the 2D inversion of PDIP resistivity for all 5 lines together with
superimposed surface geochemistry. The resistivity response from line to line
is similar and interpreted to reflect similar geology to that observed at the
Mostaza Mine (Line 1). Note: Blue colours represents high resistivity.

 

Figure 5: Cerro Negro prospect. 3D inversion modelling of AMT data highlights
highly resistive rocks to the east of the Mostaza Fault Zone (dacitic dome
rocks) in structural contact with less resistive volcanic rocks to the west of
the MFZ.

 

Next Steps - Multiple Undrilled Targets Identified Along Trend:

 

The Cerro Negro geophysics surveys have identified several discrete
chargeability-resistivity anomalies along a 2.5 km trend south of the Mostaza
Mine, defined by survey Lines 2 through 5. These anomalies show similar
geophysical characteristics to the known Cu-Ag sulphide mineralisation
identified on Line 1-moderate to high chargeability (up to 12-14 ms)
coincident with high resistivity-suggesting potential for sulphide-bearing,
silicified bodies at depth. See Figures 3 and 4.

 

Each of these targets coincides with mapped zones of alteration and anomalous
surface Cu-Ag geochemistry. All of the targets are untested by drilling.
Together, they represent a compelling cluster of high-priority targets that
may reflect a network of stacked or sub-parallel mineralised bodies along the
broader Mostaza Fault trend.

 

Integration of these geophysical results with geological mapping and surface
assays is ongoing and will inform final drill planning for Phase III
exploration.

 

  References:

1.    RNS 8981Q (14 July 2025): Gradient Array IP Anomaly Extends for 2.5km
S of Mostaza Cu-Ag Mine

2.    RNS 3120K (31 Oct 2024): Cerro Negro Exploration Results Up To 4.64%
Cu and 177ppm Ag

3.    RNS 5182Y (26 Feb 2025): Cerro Negro assays return 20m of 3.3% Cu,
270g/t Ag

4.    RNS 9022A (17 Mar 2025): Exceptional results confirm potential of
Mostaza

5.    RNS 8896D (07 Apr 2025): Further exceptional assay results from
Mostaza

6.    RNS 1375O (24 June 2025): Exceptional Drilling Results Continue at
Mostaza (https://irtools.co.uk/82/story/f5b66dcf-4cf8-4edd-8484-c582235ad460)

 

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

 

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.

 

This information is provided by RNS, the news service of the London Stock Exchange. RNS is approved by the Financial Conduct Authority to act as a Primary Information Provider in the United Kingdom. Terms and conditions relating to the use and distribution of this information may apply. For further information, please contact
rns@lseg.com (mailto:rns@lseg.com)
 or visit
www.rns.com (http://www.rns.com/)
.

RNS may use your IP address to confirm compliance with the terms and conditions, to analyse how you engage with the information contained in this communication, and to share such analysis on an anonymised basis with others as part of our commercial services. For further information about how RNS and the London Stock Exchange use the personal data you provide us, please see our
Privacy Policy (https://www.lseg.com/privacy-and-cookie-policy)
.   END  MSCDZGMRKZRGKZG