REG - Great Southrn.Copper - GSC Expands Target at Mostaza Mine, Cerro Negro

Great Southern CopperAnnouncement

03/09/2024 07:00

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RNS Number : 6179C  Great Southern Copper PLC  03 September 2024

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.

 

3 September 2024

 

Great Southern Copper plc

("GSC" or the "Company")

 

GSC Expands Target at Mostaza Cu-Ag-Au Mine, Cerro Negro Project

 

Permitting for drilling at Mostaza mine in progress

 

Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold and
lithium exploration in Chile, is pleased to announce that the scale of the
target for the Company's maiden drilling programme at the Mostaza mine has
increased due to the recognition of significant zones of additional Cu-Ag
mineralisation in historical drill-hole assays and surface rock chip samples.
Preparations for the start of drilling continue with archaeological and
environmental surveys now completed, and the selection of the drilling company
via tender.

 

Highlights:

·    Historical drilling at the Mostaza mine included 25 diamond holes for
a total of 1,024m. Drilling targeted high-grade lenses of Cu-Ag mineralisation
with intercepts above 1% Cu summarised on historical plans and sections.
Intercepts below this grade were not shown.

·    16 of the 25 historical holes were finished in anomalous copper
mineralisation (>0.1% Cu) and 4 of the holes failed to reach the high grade
target.

·    Ongoing compilation of the historical data, together with
re-interpretation and 3D modelling of assays and geology has identified a
significant halo of additional copper mineralisation located either side of
the high-grade lenses. These haloes represent an important expansion of the
mineralised potential as shown by the following examples calculated using a
cut-off of 0.1% Cu:

§ VDH4: 17m @ 0.62% Cu and 45.06ppm Ag from 18m, expanded to

·    40m @ 0.4% Cu and 23.08ppm Ag from 0m.

§ VDH9: 18m @ 0.72% Cu and 31.7ppm Ag from 18m, expanded to

·    40m @ 0.44% Cu and 16.55ppm Ag from 0m.

§ EDH15: 14m @ 1.92% Cu and 118ppm Ag from 36m

·    Incl 8m @ 2.63% Cu and 153ppm Ag from 37m, expanded to

·    54m @ 0.62% Cu from 10m (Ag assays not continuous).

§ EDH24: 8m @ 0.88% Cu and 69.0ppm Ag from 57m, expanded to

·    28m @ 0.38% Cu from 44m (Ag assays not continuous), and

§ EDH25: 6m @ 1.05% Cu and 81.0ppm Ag from 49m, now expanded to

·    33m @ 0.53% Cu from 46m (Ag assays not continuous).

·    In addition, the inclusion of this additional mineralisation allows
for inclusion of drill hole intercepts not considered in the original
high-grade resource calculation, such as:

·    VDH1: 31m @ 0.48% Cu and 18.04ppm Ag from 0m.

·    The Cu-Ag halo mineralisation has the potential to significantly
increase the size of the Mostaza deposit.

·    Preparation for the start of drilling at Mostaza is underway with
archaeological and environmental surveys completed and a drill contractor
selected via bidding process.

·    On-going exploration at Cerro Negro identifies additional copper
mineralisation hosted in multiple structures parallel to the Mostaza trend
further expanding global copper potential.

 

Cerro Negro is situated within the Company's Especularita project ideally
located close to national infrastructure including main highways, powerlines,
and towns. The project is located 170km from the port city of Coquimbo, and
130km from Antofagasta Minerals' copper concentrate port at Los Villos. The
area lies at an elevation between 800 and 1200m and is accessible year-round
for all exploration and mining activity (Figure 1).

 

The project is located within the north-south trending Cretaceous metallogenic
belt that includes Teck's Carmen de Andacollo Cu-Au Mine 80km to the north,
and Pucobre's El Espino Cu-Au development project 30km to the south. At
Especularita, this under-explored belt intersects with a northwest-trending
structural corridor that controls the "Colorada" advanced argillic lithocap
and extends to the Piuquénes porphyry Cu-Au deposit in Argentina.

 

Sam Garrett, Chief Executive Officer of Great Southern Copper, said:
"Exploration at Cerro Negro is rapidly advancing with three key objectives -
drill beneath the historic Mostaza open pit to develop a high-grade
copper-silver-gold resource, expand the Mostaza deposit along strike targeting
extensions to the mineralised structures, and explore at depth targeting
large-scale porphyry copper type deposits.

 

"It is very encouraging to identify this additional potential before any
metres have even been drilled at Mostaza. This newly recognised mineralisation
has the potential to significantly increase the size of the Mostaza deposit
and provides additional optionality for potential future mining operations.

 

"The discovery of additional copper-mineralised structures hosted in the
advanced argillic lithocap above the Mostaza mine is also very significant in
terms of our porphyry copper exploration at Cerro Negro. The potential of
these anastomosing mineralised structures to grade downward into porphyry type
mineralisation is a genuine target vector.

 

"The copper bank at Cerro Negro is building and we eagerly await the start of
drilling. Drill sites have been selected and reviewed by the drilling
contractor and permitting for the drilling programme is progressing with
archaeological and environmental surveys already completed."

 

Mostaza Cu-Ag-Au Mine:

The Mostaza Cu-Ag-Au gold mine at Cerro Negro was previously owned and mined
by Antofagasta Minerals with mixed oxide and sulphide ores processed at their
nearby Parral flotation plant(1) also located within GSC's group of
concessions.

 

High-grade Cu-Ag-Au mineralisation at Mostaza is hosted in a north-south
trending shear zone which is intruded by felsic dykes and breccias which have
been overprinted by intense advanced argillic to phyllic alteration. Copper
mineralisation is dominated by hypogene stromeyerite (copper-silver) and
chalcocite, covellite, digenite, bornite, plus lesser chalcopyrite and
pyrite(1) as disseminations and in quartz veinlets, crackle networks and
breccias

 

The high-grade mineralisation forms steeply-dipping tabular bodies, or lenses,
which appear to "pinch and swell" along the shear zones, however, this
interpretation may be a result of low drill density. Five lenses have been
identified within the Mostaza "Near-Mine" area with historical mining activity
at Lenses 1 and 2.

 

Historical exploration is limited to the near-mine area with 25 diamond holes
completed for a total of 1,024m (Figure 1). Significant intercepts for the
drilling are summarised in Table 1 below. Only 14 of the 25 holes are believed
to have reached target depth with the deepest hole drilling to only 92m. In
1981 these results, together with rock channel sampling of mine workings, were
used to calculate an internal non-JORC mineral resource estimate for Lens 1
and 2 reported at 190,600t of measured & indicated sulphide with grades of
1.2% Cu, 80 g/t Ag, and 0.45 g/t Au, plus an additional 63,000t of inferred
sulphide resource at depth(1) (The 1981 Historical Mineral Resource Estimate -
HMRE)(2).

 

The drilling clearly demonstrated that the high-grade Cu-Ag mineralisation is
open both at depth and along strike, however, no further drilling or
exploration activity has since been conducted at Mostaza.

 

3D Modelling of the Mostaza Cu-Ag Deposit:

Investigation of the historical drill data and 3D modelling of the deposit by
GSC has subsequently revealed that the high-grade, structurally controlled
mineralisation at Mostaza is enveloped by a broad halo of lower-grade copper
mineralisation (>0.1% Cu).

 

Significantly, 16 of the 25 historical drill holes were terminated in
anomalous copper mineralisation of >0.1% Cu plus 4 of the holes reportedly
failed to reach target depths. Significant intervals (>0.1% Cu) are
reported in Table 1. Consequently, to date, the extent of the mineralisation
at Mostaza is only limited by the depth of drill holes.

 

3D modelling of the deposit is in progress to map the high-grade
mineralisation and controlling structures, plus assisting with drill targeting
(Figure 2). In addition, calculation of the 0.3% Cu cut-off shell clearly
demonstrates the increased size of the deposit (Figure 3).

 

 

 Hole_ID  From_m  To_m  Interval  Cu_%  Ag_ppm  Notes:
 VDH1     0       31    31        0.48  18.04   Hole terminated in mineralisation
 incl     0       3     3         0.9   27
 and      10      14    4         0.96  65
 VDH2     0       35    35        0.17  2.23    Hole terminated in mineralisation
 incl     9       14    5         0.23  7.8
 VDH3                                           No significant. Hole terminated in mineralisation
 VDH4     0       40    40        0.4   23.08   Hole terminated in mineralisation
 incl     18      35    17        0.62  45.06
 and      26      35    9         0.91  69.22
 VDH5     0       11    11        0.16  1.82    Hole terminated in mineralisation with Cu-Ag grades increasing
 VDH6     1       10    9         0.13  0.89
          15      21    6         0.19  1.67    Hole terminated in mineralisation with Cu-Ag grades increasing
 VDH7                                           No significant intercept
 VDH8     0       22    22        0.29  4.23    Hole terminated in mineralisation
 incl     0       6     6         0.35  4.33
 and      15      22    7         0.34  7.12
 VDH9     0       40    40        0.44  16.55   Hole terminated in mineralisation
 incl     18      36    18        0.72  31.7
 incl     19      23    4         1.05  55.75
 and      25      30    5         1.04  50
 VDH10    0       9     9         0.18  na
          11      13    2         0.2           Hole terminated in mineralisation
 VDH11    1       41.3  40.3      0.17  1.06    Hole terminated in mineralisation
 EDH12                                          No significant intercept
 EDH13                                          No significant intercept
 EDH14    6       12    6         0.12  na
 EDH15    10      63    54        0.62  na
 incl     33      52    19        1.52  91.95
 incl     36      51    15        1.82  113.67
 incl     37      45    8         2.63  153
          70      86    16        0.13  na
 EDH16    23      30    7         0.12  na
          31      36    5         0.11  na
          38      43    5         0.1   na
          46      51    5         0.12  na
          55      87    32        0.15  na
          88      90    2         0.1   na
 EDH17    6       9     3         0.1   na
          13      24    11        0.12  na
          31      43    12        0.12  na
          44      52    8         0.14  na
          54      57    3         0.1   na
          65      79    14        0.14  na
          82      87    5         0.17  na
          88      91    3         0.12  na      Hole terminated in mineralisation
 EDH18    10      12    2         0.1   na
          19      43    24        0.35  na
 incl     27      30    3         1.73  101.67
          47      54    7         0.12  na
          56      65    9         0.12  na
 EDH19    16      24    8         0.11  na
          27      36    9         0.13  na
          43      48    5         0.52  37      Hole terminated in high grade Cu-Ag
 EDH20    10      19    9         0.1   na
          22      25    3         0.1   na
 EDH21                                          No significant intercept
 EDH22    0       3     3         0.12  na
          5       14    9         0.13  na
          18      49    31        0.14  na      Hole terminated in mineralisation with Cu-Ag grade increasing
 EDH23    15      26    11        0.12  na
          33      49    16        0.47  na      Hole terminated in mineralisation
 incl     39      46    7         0.87  57.29
 EDH24    35      41    6         0.12  na
          44      72    28        0.38  na      Hole terminated in mineralisation
 incl     57      68    11        0.75  52.73
 incl     57      65    8         0.88  69
 EDH25    46      79    33        0.53  na      Hole terminated in mineralisation
 incl     48      58    10        0.77  54.6
 incl     49      55    6         1.05  81
 and      62      71    9         0.92  72.56

 

Table 1: Significant intercepts for historical resource and exploration drill
holes at Mostaza mine, Cerro Negro. New intervals calculated using a 0.1% Cu
cut-off are indicated in italics.

 

Figure 1: Map of the Mostaza Mine area adapted from the 1981 Historical
Mineral Resource Estimate, showing historical drill holes and geological
cross-sections on the pre-mining topography. To date mining activity has only
centred on Lenses 1 and 2, with minimal exploration and drilling outside of
the mine area.

 

Figure 2: Oblique view of the Mostaza trend looking to the SE showing Lens 2
(red and yellow) and the surface expression of the other lenses and alteration
zones along trend to the south.

 

Figure 3: Oblique section view of the Mostaza open pit looking to the NNE
showing high-grade Cu-Ag-Au mineralisation (>1.0% Cu) in Lens 2 (red) with
newly recognised halo mineralisation >0.3% Cu (orange). Historical drill
holes traces are shown in blue.

 

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:

1.     RNS 4027V (08 July 2024): GSC signs Cerro Negro Purchase Option
Agreement.

2.     1981 Mineral Resource Estimate; Internal report by Jeraldo Gold
Mining.

 

 

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
(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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