Great Southern Copper plc (LON:GSCU) Geophysics Surveys Commence at Cerro Negro

Geophysics Surveys Commence at Cerro Negro Prospect, Especularita Project

IP and AMT surveys to target extensions of high-grade Cu-Ag mineralisation at Mostaza

Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold exploration in Chile, is pleased to announce that it has commenced pole-dipole induced polarisation (PDIP) and audio frequency magneto-telluric (AMT) geophysics surveys on the Cerro Negro prospect at the Company’s Especularita Project in Chile.

Highlights:

·    Exploration geophysics surveys commence at Cerro Negro prospect

·    Four lines of PDIP and AMT surveys to detect potential extensions of high-grade Cu-Ag mineralisation below and along trend of the Mostaza mine

·    Survey results to assist in targeting Phase III exploration drilling at Cerro Negro up to two kilometres south of the Mostaza mine where Phase I drilling intersected significant Cu-Ag mineralisation including:

Ø ¹CNG25-DD001: 20.0m of 3.31% Cu, 269.89g/t Ag from 27m

Ø ²CNG25-DD005: 12.0m of 4.24% Cu, 369.5 g/t Ag from 40m, and

Ø ³CNG25-DD007: 33m of 1.96% Cu and 60.6 g/t Ag from 87m

·    Phase II drilling results for holes CNG25-DD010 to CNG25-DD025 are pending

·    GSC holds options to 100% of the prospects that make up its Especularita Project

·    Excellent access to national infrastructure including roads, power, port and townships

Sam Garrett, CEO for Great Southern Copper, said: “These important geophysical surveys will play a critical role in guiding our Phase III exploration drilling at Cerro Negro. Phases I and II relied on surface exploration results and we now want to explore deeper, both beneath the known mineralisation at Mostaza and along trend to the south.

“The IP survey is designed to detect the disseminated Mostaza-style sulphide mineralisation and resistivity contrasts of altered rocks down to some 200m depth. The AMT survey is run in parallel and provides resistivity data down to many hundreds of metres depth. The four survey lines will test a two kilometre strike length of the Mostaza mineralised system, however, mineralisation remains open still further to the south.

“We look forward to announcing the results of these surveys as well as the drilling results for Mostaza and Viuda Negra.”

Geophysics surveys, Cerro Negro:

The Company has contracted Southern Rock Geophysics (SRG) of Santiago, Chile to complete four initial pole-dipole induced polarisation (PDIP) and coincident audio frequency magnetotelluric (AMT) survey lines across the Mostaza trend (see Figure 1) at Cerro Negro. The PDIP will detect variations in electrical chargeability expected of the disseminated and crackle hosted sulphide mineralisation and resistivity variations expected of the altered lodes down to some 200 metres (m). AMT will detect variations in resistivity to several hundred metres depth.

Line 1 is designed to cross the Mostaza Mine area to test the depth extension of west dipping and subvertical high-grade Cu-Ag mineralisation reported in the following holes:

·    ¹CNG25 DD001: 20m @ 3.31 % Cu, 269.89 g/t Ag from 27m

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

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

·    ²CNG25 DD003: 18.6m @1.85 % Cu, 146.58 g/t Ag from 36.6m

o  including 13m @ 2.48 % Cu, 198.09 g/t Ag from 39m

o  including 1m @ 4.64 % Cu, 406.00 g/t Ag, from 50m

·    ²CNG25 DD005: 21m @ 2.89 % Cu, 246.71 g/t Ag from 35m

o  including 7m @ 5.08 % Cu, 449.57 g/t Ag from 45m

o  including 2m @ 6.05 % Cu, 547.50 g/t Ag from 45m

Line 2 will test the depth extent of mineralisation in Lenses 3, 4 and 5 which included the following drill results:

·    ³CNG25 DD007: 33m @ 1.96% Cu and 60.6 g/t Ag from 87m

o  Including 3.85m @ 5.21% Cu and 318.2 g/t Ag from 88m, and

o  Including 2.5m @ 9.67% Cu and 175.4 g/t Ag from 116.4m

Lines 3 and 4 will test across undrilled outcrops along trend to the south, where mapping has identified altered and mineralised rocks that return assay grades up to 4.64% Cu and 177ppm Ag in rock grab and channel samples⁴.

Figure 1. Plan view of the Cerro Negro Prospect, showing the Mostaza Mine and the southward extension of observed alteration and mineralisation (red) to be investigated by the PDIP and AMT survey lines (yellow). Mineralisation remains open further to the south of Line 4. North to the right.

References:

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

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

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

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

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