Drilling Commences at Viuda Negra

The following amendment has been made to the "Scout Diamond Drilling Commences at Viuda Negra Prospect, Viuda" announcement released on 23/04/2025 at 07:17 under RNS No 8279F

Correcting the figure "45g/t Ag" on the third bullet point in the Highlights section to "145g/t Ag"

All other details remain unchanged.

The full amended text is shown below.

Great Southern Copper plc

("GSC" or the "Company")

Scout Diamond Drilling Commences at Viuda Negra Prospect, Viuda

Targeting epithermal-porphyry style Au-Ag-Cu mineralisation

Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold exploration in Chile, is pleased to announce that drilling has commenced on its Viuda Negra prospect located within the Especularita project.

Highlights:

• Scout diamond drilling commences at Viuda Negra prospect targeting Au-Ag-Cu mineralisation
• Initial programme comprises 2 - 4 scout holes for a total of up to 500m
• Drilling targeting outcropping porphyry-epithermal style alteration with rock chip samples assaying up to 4.2g/t Au, 145g/t Ag and 0.56% Cu1
• GSC holds options to own 100% of the Viuda and Viuda Negra prospect
• Project located in coastal metallogenic belt with excellent access and infrastructure

Sam Garrett, CEO for Great Southern Copper in Chile, said: "We are excited to commence scout drilling at the Viuda Negra prospect where recent exploration by GSC has identified outcropping evidence of epithermal-porphyry type mineralisation with assay grades in rock chips and channel chip samples ranging up to 4.2g/t Au, 145g/t Ag and 0.56% Cu.

"The style of gold-rich sheeted veining outcropping at Viuda Negra and elsewhere across the Viuda prospect, is characteristic of Maricunga type porphyry gold deposits in Chile. Significantly, this style of gold deposit has not previously been recognised in the coastal belt of Chile.

"The Viuda and Viuda Negra targets emphasise the exciting depth of the Especularita drilling pipe-line which is further enhanced by the current environment of record gold and silver prices. The location and scale of the Especularita project coupled with the deposit style and commodity optionality on offer remains a key differentiating factor for GSC."

Viuda Negra Prospect:

Follow-up mapping of anomalous soil geochemistry results at Viuda has discovered outcropping sheeted and stockworked, banded quartz-magnetite veins at Viuda Negra, located 1km to the northeast of Changay Hill (Figure 1), that are characteristic of Au-rich porphyry systems in Chile. Subsequent channel chip sampling across the outcrops has returned assays up to 1m at 4.2 g/t Au and 0.12% Cu1. Nearby several epithermal-style ledges were also discovered with intense multi-stage quartz veinlet stockworks associated with epithermal type advanced argillic alteration. Rock chip sampling of several of the ledges returned values up to 145 g/t Ag and 0.56% Cu1 (Figure 2).

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Figure 1. Location of the Viuda Negra prospect, Viuda project, Especularita (left) and Geological map of Viuda and Viuda Negra prospects (right). The roughly circular zone of albite-pyrite-clay alteration coincides well with satellite imagery and soil geochemistry.

Figure 2: Geology and recent rock chip geochemistry results for Viuda Negra prospect, Viuda.

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Drilling:

Scout diamond drilling has commenced at Viuda Negra to test the outcropping ridges of anomalous gold and silver mineralisation identified by surface mapping and sampling. Up to 4 drill holes are proposed for a total of up to 400 - 500m.

Hole VNE25-DD001 is currently at 70m depth and testing sheeted, Maricunga style quartz-magnetite vein alteration at Cruachan Ridge where channel sampling has returned assay grades up to 4.2g/t Au and 0.12% Cu (Figure 2). The hole has intersected zones of quartz fracture-veining and hydrothermal brecciation (Figure 3). Hole VNE25-DD002 is planned to test epithermal style alteration outcropping at Scarlett Ridge with anomalous silver grades up to 29.9g/t Ag (Figure 2).

Figure 3: Drill core from VNE25-DD001 demonstrating Maricunga-style quartz fracture-veining (l) and hydothermal brecciation (r).

References:

• RNS 2553F (16 April 2025): Results for scout RC drilling at Viuda

Forward Looking and Cautionary Statements