REG - Great Southrn.Copper - Cerro Negro assays return 20m @3.3% Cu & 270g/t Ag

Great Southern CopperAnnouncement

26/02/2025 07:15

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RNS Number : 5182Y  Great Southern Copper PLC  26 February 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.

 

26 February 2025

 

Great Southern Copper plc

("GSC" or the "Company")

 

First assays from Cerro Negro return 20m @ 3.3% Cu and 270g/t Ag from 27m
depth

 

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

 

Great Southern Copper plc (LSE: GSCU), the company focused on
copper-gold-lithium exploration in Chile, is pleased to report exceptional
first assay results from Phase I drilling at the Mostaza Mine, Cerro Negro.

 

Highlights:

 

·    Assay results received for hole CNG25 DD001 drilled at the historical
Mostaza Mine include:

 

Ø 20m @ 3.31% Cu, 269.89g/t Ag from 27m depth

Ø Including 7m @ 5.72% Cu, 489.57g/t Ag from 31m depth

Ø Including 3m @ 6.62% Cu, 562.67g/t Ag from 35m depth

 

·    Peak assay grades of 6.79% Cu, 583g/t Ag and 0.35% Sb

·    CNG25 DD001 assay grades for Cu and Ag over 600% higher than
historical grades reported for adjacent 1980's drillhole EDH25(1) indicates
potential for significant under-reporting of historical assay results

·    Strike and depth continuity of visible mineralisation confirmed by
GSC drill holes(2) with mineralisation open in all directions

·    Assay results for remaining Phase I drill holes, CNG25 DD002 - 009,
are pending

·    Planning for follow-up resource and exploration drilling underway

·    GSC holds option to own 100% of the Mostaza mine and Cerro Negro
project

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

 

Sam Garrett, Chief Executive Officer of Great Southern Copper, said: "This is
a tremendously significant result for both copper and silver. These
exceptional and exciting assay grades demonstrate that the former Mostaza mine
has the potential to be a high-grade high-value Cu-Ag deposit.

 

Drill hole CNG25 DD001 was designed specifically to verify the width and grade
of mineralisation reported in historical drill hole EDH25, which reported
25.33m of 0.53% Cu. Drill samples for EDH25 were assayed at uncertified local
facilities in the early 1980's so it was important to confirm the veracity of
these results from the outset. Assay grades for CNG25 DD001 are significantly
higher than the historically reported EDH25 results and if this is confirmed
in other GSC drillholes, it could have a positive impact on the potential
economics of the Mostaza resource.

 

We are hopeful that the remaining GSC holes at Mostaza will return further
exciting results and look forward to updating the market. Planning for the
next phase of drilling plus metallurgical test work is already underway."

 

Results of diamond drillhole CNG25 DD001

 

Diamond drillhole CNG25 DD001, the first hole in GSC's Phase I drilling
programme at Cerro Negro, is located within the historical Mostaza open pit
mine (Figure 1) and was designed to confirm the width, grade and style of
mineralisation cut by historical drillhole EDH25 that reported 25.33m at 0.53%
Cu, including 6m at 1.05% Cu and 81g/t Ag(1). Due to access issues CNG25 DD001
was not drilled exactly parallel to EDH25, however, it was oriented to pass as
close as possible to the historical intercept, perhaps within metres.

 

Hole CNG25 DD001 returned significant assay grade intervals of 20m @ 3.31% Cu
and 269.89g/t Ag from 27m depth, including 7m @ 5.72% Cu and 489.57g/t Ag from
31m depth, including 3m @ 6.62% Cu and 562.67g/t Ag from 35m depth which
represents an approximate 600% increase in the historically reported grades
for EDH25. All assay results are shown in Table 1. The broad, high-grade
intercept includes peak Cu-Ag grades of 6.79% Cu and 583g/t Ag. The
mineralised lens is also weakly anomalous in Sb-As and exhibits pathfinder
anomalism for Bi-Cd-Li-S-Te-Zn.

 

Mineralisation in hole CNG25 DD001 is confined to a 20m wide, north-south
trending structurally-controlled lode, or "lens", that dips moderately steeply
to the west (Figure 1). Copper mineralisation comprises abundant
disseminations, veinlets, crackle networks, and breccia matrix fillings of
hypogene black to dark metallic grey chalcocite with lesser bluish bornite and
traces of chalcopyrite and pyrite (Figure 2). Petrographic confirmation is
pending, however, the copper mineralogy may include other silver-rich copper
minerals such as stromeyerite (AgCuS) for example.

 

Fracture density within the 20m mineralised intercept is a dominant control on
mineralisation intensity with grades ranging from 0.515% Cu and 23.9g/t Ag to
6.79% Cu and 583g/t Ag (illustrated in Figure 2). Within the 7m high-grade
intercept zone, however, grades are more consistent ranging from 3.65% Cu and
305g/t Ag up to 6.79% Cu and 583g/t Ag. Anomalous silver (>0.1g/t Ag) is
evident in the enclosing host-rocks up to 27m from the mineralisation zone
with grades up to 3.96g/t Ag.

 

Lens 2 host rocks are intensely altered and appear to comprise multiple
generations of breccia, tuffisite, and felsic intrusive (Figure 2) altered to
texturally destructive illite ± montmorillonite overprinted by probable
alunite ± dickite ± pyrophyllite (to be confirmed by petrographic studies).
The Cu-Ag mineralised lens exhibits sharp contacts and is bounded to the east
and west by faults intruded by narrow andesite to rhyolite dykes. Outside the
bounding dykes and faults, the enclosing wall rocks consist of an east-dipping
bedded sequence of fresh, black volcanic lava flows and red, hematite-rich
phreatic and/or phreatomagmatic breccias that might be part of a large
dome-diatreme complex outcropping to the east.

 

The high-grade Cu-Ag mineralogy type and associated advanced argillic style
alteration suggests the lodes at Mostaza are part of a high-sulphidation
epithermal system, potentially related to a yet-to-be-discovered porphyry
style deposit occurring at depth.

 

The Lens 2 mineralisation is interpreted to form one of a number of Cu-Ag rich
bodies mapped at surface (Figure 3) which have historically been interpreted
as discrete "lenses" but which collectively have the potential to make up an
anastomosing network of structurally controlled zones of mineralisation
continuous over a strike length of greater than 1-2km.

 

The results of CNG25 DD001 and subsequent holes DD002 - 005 targeting
mineralisation beneath the existing Mostaza open pit demonstrate that the
deposit continues at depth and along strike from the historical drilling and
is open in all directions (Figure 4).

 

Core preparation, sampling and assaying

 

The Mostaza drill core is being processed for geological, geotechnical,
petrophysical and geochemical data by GSC staff. Sampling intervals are
selected principally on geologic boundaries and may vary in length up to 2m.
The core is cut into two halves using an electric diamond brick saw with
half-core samples each allocated a unique identifier code and bagged-tagged
separately. Samples for each complete hole are transported by GSC personnel to
ALS laboratories in Santiago, Chile for sample preparation (drying, weighing,
crushing and grinding). A final 200g aliquot of each sample is forwarded by
ALS to their laboratories in Lima, Peru where it is assayed for Au (by 30g
fire assay with ICP-AES finish method) plus a suite of 48 base metals and
trace elements including Cu and Mo (by four acid digest ICP-MS method).

 

Sampling and assaying QAQC protocols employed by the company for this drilling
project include routine insertion of standard reference materials including
standards and blanks. Results for each SRM is assessed to monitor the accuracy
and precision of the assay data from ALS for the core samples.

 

Next steps

Planning and permitting for Phase II diamond drilling at Mostaza is underway
and expected to include resource and exploration drilling. Metallurgical
studies of drill core, stockpiles and tailings are also being planned.
Extensions of mineralisation at depth and along trend under cover may also be
targeted with geophysical surveys.

 

 

 

Figure 1: Cerro Negro Project, Mostaza Mine: Preliminary geological cross
section interpretation through drillholes CNG25 DD001 (this release) and DD005
illustrating the relationship to historical drillholes EDH's15, 23 and 25.

 

 

Figure 2: Cerro Negro Project, Mostaza Mine. Photograph of core from hole
CNG25 DD001, Left: The black disseminations, veinlets and crackle fill are
Cu-Ag sulphide and sulfosalt minerals possibly including chalcocite in
association with chalcedonic silica and minor baryte gangue cutting pinkish
advanced argillic alteration (1m @ 4.9% Cu, 455g/t Ag from 31m). Right:
similar sulphide and sulfosalt minerals associated with pale green
intermediate argillic alteration (1m @ 1.9% Cu, 139g/t Ag from 43m).

 

Figure 3: Cerro Negro Project, Mostaza Mine: Plan map showing the approximate
locations of mineralised lenses at surface, historical drillholes, and GSC
drillholes. Hole CNG25 DD001 reported in this release is highlighted in
yellow. Note the scale of the known system.

 

 

Figure 4: Cerro Negro Project, Mostaza Mine: Preliminary interpreted long
section of Lens 2 illustrating the location of where GSC's Phase 1 drillholes
are projected to intersect the hanging wall of the mineralised lens (black
circles). Hole CNG25 DD001 (this release) is highlighted in yellow. The
apparent thickness of visible copper mineralisation is highlighted in bold
below each intersection point. Note that mineralisation remains open at depth
and along strike. Historical resource blocks, underground mine workings,
channel sample and drillhole assay results (coloured) are shown for reference.
(GSC has not been able to independently verify the historical channel sample
or drill hole assay results).

 

 SAMPLE ID  FROM (m)  TO (m)  LONG (m)  LITHOLOGY          Cu %   Ag g/t  Sb ppm
 994564     0.0       2.0     2.0       Black Breccia      0.017  0.43    13.45
 994565     2.0       4.0     2.0                          0.057  3.96    30.6
 994566     4.0       6.0     2.0                          0.007  0.62    2.91
 994567     6.0       8.0     2.0                          0.008  0.41    4.66
 994568     8.0       10.0    2.0       Red    Breccia     0.001  0.05    1.84
 994569     10.0      12.0    2.0                          0.002  0.07    2.01
 994571     12.0      14.0    2.0                          0.001  0.06    2.1
 994572     14.0      16.0    2.0                          0.003  0.19    3.62
 994573     16.0      18.0    2.0                          0.002  0.1     3.68
 994574     18.0      20.0    2.0                          0.004  0.22    5.38
 994575     20.0      22.9    2.9                          0.002  0.1     3.6
 994576     22.9      24.6    1.7                          0.032  1.01    6.89
 994578     24.6      26.0    1.4       Dyke               0.010  0.12    3.21
 994579     26.0      27.0    1.0                          0.012  0.7     93.2
 994580     27.0      28.0    1.0       LENS 2             2.670  193     666
 994581     28.0      29.0    1.0                          1.850  169     464
 994582     29.0      30.0    1.0                          1.530  138     328
 994583     30.0      31.0    1.0                          1.650  129     491
 994585     31.0      32.0    1.0                          4.910  455     377
 994586     32.0      33.0    1.0                          5.600  451     1215
 994587     33.0      34.0    1.0                          6.050  528     3460
 994588     34.0      35.0    1.0                          3.650  305     1320
 994589     35.0      36.0    1.0                          6.600  530     868
 994590     36.0      37.0    1.0                          6.790  575     206
 994591     37.0      38.0    1.0                          6.460  583     146
 994592     38.0      39.0    1.0                          2.380  182     352
 994594     39.0      40.0    1.0                          0.515  23.9    109.5
 994595     40.0      41.0    1.0                          1.550  74.9    1130
 994596     41.0      42.0    1.0                          1.145  78.1    2080
 994598     42.0      43.0    1.0                          2.460  158     2480
 994599     43.0      44.0    1.0                          1.905  139     758
 994600     44.0      45.0    1.0                          1.995  152     490
 994601     45.0      46.0    1.0                          4.750  395     1055
 994602     46.0      47.0    1.0                          1.750  139     687
 994603     47.0      48.0    1.0       Dyke               0.393  24.7    85.8
 994605     48.0      49.0    1.0                          0.013  0.93    39.3
 994606     49.0      50.0    1.0                          0.005  0.44    26.4
 994607     50.0      51.0    1.0       Red    Breccia     0.006  0.41    27.8
 994608     61.0      62.0    1.0                          0.002  0.15    6.26
 994609     71.0      72.0    1.0                          0.001  0.08    10.35
 994610     81.0      82.0    1.0                          0.003  0.09    17.45
 994612     91.0      92.0    1.0                          0.00   0.12    13.65
 994613     101.0     102.0   1.0                          0.00   0.06    8.6

 

Table 1. Cerro Negro Project, Mostaza Mine; CNG25 DD001 assay results for Au,
Ag and Cu.

 

 

Cautionary note:

The Company cautions that all references to "resources", "mineral resources",
or "mineral resource estimates" in this RNS are historical and were prepared
and reported prior to the implementation of the JORC code and therefore are
non-JORC compliant. The Company advises that the resource categories used in
the historical estimates, for example "measured, indicated, demonstrated and
inferred", may not have the same meaning or degree of confidence as current
JORC categories. Historical records indicate that the quoted non-JORC
resources were calculated using the polygonal method based on underground
sampling, 1024m of drilling in 25 holes, and geological cross-sections and
level plans. GSC is presenting this information for historical context only
and is not treating it as a current mineral resource estimate. The Company has
not been able to independently verify the results of historical drilling or
mine channel samples. References to mineralised intervals are considered
apparent thicknesses as there is not sufficient geological information to
calculate true thickness of mineralised intercepts at this time.

References:

1.            RNS 2189S (06 January 2025): Diamond drilling
commences at Cerro Negro

2.            RNS 4946X (18 February 2025): Diamond Drilling
Programme Completed at Mostaza Mine

 

 

 

Enquiries:

 

 Great Southern Copper plc
 Sam Garrett, Chief Executive Officer      +44 (0) 20 4582 3500

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

 Gracechurch Group
 Harry Chathli, Alexis Gore, Henry Gamble  +44 (0) 20 4582 3500

 

 

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. In addition, the Company has the option to acquire rights to 100% of
a lithium project located in the Salar de Atacama district of Chile. Chile is
a globally significant mining jurisdiction being the world's largest copper
producer and the second-largest producer of lithium.

 

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.

 

The Company's Monti Lithium project is strategically located in the pre-Andean
region of Salar de Atacama which is Chile's premier lithium-producing region
with well-established lithium mining operations and infrastructure.

 

Great Southern Copper is strategically positioned to support the global market
for copper and lithium - both critical battery metals 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 and Li deposits as well as high-grade Cu-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.

 

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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