High Grade Ag-Cu in Rock Samples Expands Monolith Target at Cerro Negro, Especularita
Second drill rig arrives at Mostaza to expand Phase III drilling programme
Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold-silver exploration in Chile, is pleased to announce that the results of its channel rock chip sampling programme at the Monolith Cu-Ag prospect (“Monolith”) significantly enhances the mineralised footprint at Cerro Negro, and that a second diamond drill rig has arrived on site at the Mostasa Mine (“Mostaza”).
Highlights:
· 48 rock channel samples collected at Monolith with assay grades up to 271g/t Ag, 2.05% Cu
· Samples average 35.4g/t Ag and 0.31% Cu despite evidence of surface leaching
· Results define a zone of mineralisation greater than 50 metres (“m”) wide
· Mineralisation open to the south and southeast where exploration is continuing
· Second diamond drill rig arrives on site to advance Mostaza Phase III drill programme
· Company holds the option to earn 100% of the Cerro Negro prospect
· The Especularita Project is located at low elevation with excellent access to mining infrastructure and services
Prospect-scale mapping and sampling have continued across the Cerro Negro prospect with the aim of determining the potential for the Mostaza style high-grade, structurally-controlled Cu-Ag mineralisation to extend along strike to the south and east and to investigate potential for, and vector towards, porphyry Cu style mineralisation.
Sam Garrett, Chief Executive Officer of Great Southern Copper, said: “With copper and silver prices at record highs, these high-grade results are both exciting and highly significant since they further demonstrate and expand the scale potential of the Cerro Negro Cu-Ag prospect. With Phase III drilling underway at Mostaza, the team is also working in parallel to advance exploration across additional targets within the Cerro Negro prospect area to expand the mineralised footprint.
“The Company has previously reported results of high-grade Cu-Ag in rock chip samples along the Mostaza Fault up to 2.5 kilometres to the south of the Mostaza mine. These results now extend that work to the east of Mostaza, reinforcing our confidence in the broader district-scale potential of the system.
“A second diamond drill rig has arrived on site to further advance the Phase III drill programme at Mostaza. Rig 2 will initially target extensions and in-fill to the Lens 2 mineralisation. The Company looks forward to updating the market as drilling progresses and results are received”
Figure 1: Location map of GSC’s Especularita Project and Mostaza mine in Chile.
Monolith Cu-Ag prospect:
This prospect-scale mapping and sampling work follows on from reconnaissance sampling at Monolith reported in 20241 which first identified the Monolith prospect. The Monolith prospect, where artisanal miners recovered high-grade Cu-Ag from baryte-rich veins extending over 200m, is located approximately 400m to the southeast of the Mostaza mine (Figure 2, 3). The copper and silver-rich baryte veins form an anastomosing network within a broader alteration zone of silica-clay altered dacitic wall-rock up to 50m wide. High-grade Cu-Ag mineralisation is identified as green and black copper oxides on fracture surfaces, in quartz veinlets, stockworks and vein breccias and as disseminations within the altered dacite (Figure 4). In places, the silicified host-rocks are variably eroded, producing spires or “monoliths” of strongly Cu-Ag mineralised rock. Significant limonitic-goerthitic boxworks after sulphide suggest evidence of leaching of sulphides at surface.
The mineralised dacitic rocks are very similar in appearance to those observed at the bottom of the Mostaza pit and in the Lens 5 area.
Mapping and sampling is continuing at Monolith and across the Cerro Negro prospect to assist with defining further targets for exploration drilling.
Sampling and results:
Samples were collected as 1-2m channel chip samples with the exception of one sample (991641) which was taken from mine mullock. All rock samples collected are located using hand-held GPS units (WGS84 zone 19S datum, UTM coordinate system) and allocated a unique sample number using a ticket-book system.
Samples are transported from the field and delivered by Company employees to ALS Laboratories in Santiago, where they are prepared for analysis (weighed, dried, crushed and pulverised). A subsequent 200g split of each sample pulp is then forwarded to the ALS geochemical laboratory in Lima, Peru, where samples are assayed for gold (30g fire assay with ICP-AES finish, ALS code AU-ICP21) and analysed for 48 major, base and trace elements by ICP-MS following a four-acid digest (ALS code ME-MS61).
Copper assay grades for the channel chip samples range up to 2.09% Cu with 55% of samples being anomalous in copper (>0.1% Cu) – although the oxidised and leached nature of the dacitic host rock suggests that a lower threshold may still be anomalous. Silver assay grades range up to 271g/t Ag with 85% of samples anomalous in silver (>1.0g/t Ag) and 75% of samples assaying >10g/t Ag. Strongly elevated silver grades with low copper is further evidence of potential leaching of copper in the oxide profile at Monolith.
Phase III drilling update:
Four diamond drill holes (CNG25-DD026-29) have been completed to date testing the Lenses 3-5 area. A second diamond rig has arrived on site to advance the programme and will initially test in-fill and extensions to the Lens 2 mineralisation.
Figure 2: Summary map of rock chip assay results at Cerro Negro for silver (L) and copper (R).
Figure 3: New and previously reported assay results for silver (L) and copper (R) at the Monolith target, Cerro Negro prospect, Especularita.
Figure 4: Examples of visible copper mineralisation outcropping at the Monolith target, Cerro Negro.
References:
1. RNS 3120K (31 Oct 2024): Cerro Negro Results up to 4.64% Cu and 177g/t Ag.
Enquiries:
|
Great Southern Copper plc |
c/o BlytheRay |
|
Sam Garrett, Chief Executive Officer |
+44 (0) 20 7138 3204 |
