Great Southern Copper plc, the company focused on copper-gold-silver exploration in Chile, has announced the partial assay results of Hole CNG25-DD042 (DD042) recently received for its Phase III drilling programme at the Cerro Negro prospect, part of the Especularita Project. Hole CNG25-DD042 tested the interpreted southern extension of Lens 2 some 300m along trend from the Mostaza mine. The hole intersected multiple zones or lenses of base and precious metals mineralisation including significant intercepts: 21.8m @ 1.04% Cu and 52.26 g/t Ag from 73.0m, including 6.0m @ 2.56% Cu and 128.16 g/t Ag from 79.0m, and 1.6m @ 6.55% Cu and 319.75 g/t Ag from 82.0m.
An upper Pb-Zn-Ag rich silica breccia zone includes grades up to 22.4g/t Ag, 1.9% Pb and 0.34% Zn similar to the mineralisation identified in the hanging-wall to Lens 2. DD-042 results extend the Mostaza system to over 400m of strike length with mineralisation open to the south. Pb and Zn rich intervals add further evidence of a complex multiphase stacked system. Results are pending for final diamond holes and all RC drill holes.
Planning for fully funded Phase IV resource and exploration drilling is in progress. GSC holds option to 100% of the Cerro Negro project including the Mostaza mine. Project is located at low elevation with excellent access to mining-related infrastructure.
Diamond drillhole DD042 was collared about 300m south and along trend of the Mostaza Lens 2 mineralisation and drilled towards the Southwest to test for extensions of a new mineralised trend discovered by holes CNG25-DD007, DD026 and DD027, that is interpreted to be the potential southern extension of Lens 2. Some of the previous holes intercepted high-grade mineralisation over significant widths, such as hole CNG25-DD007 which intersected 33m @ 1.96% Cu and 60.6 g/t Ag from 87m. In contrast, hole DD026 intersected multiple narrow (<1m) intervals or lenses with grades up to 1.98% Cu and 94.1g/t Ag, suggesting the mineralisation might be pinching out or is overprinted by complex shearing and faulting. Hole CNG25-DD042 was designed to test to the south of this structurally complex zone to demonstrate continuity.
Near the top of the hole, it intercepted silica-sulphide assemblage mineralisation with pyrite-chalcopyrite-galena-sphalerite associated with silica-rich hydrothermal breccia on the margins of a coarse feldspar porphyry. At depth the hole intersected two intervals of crackle-veinlet and disseminated chalcocite-clay assemblage mineralisation and an aphanitic dyke as seen in Lens 2. From (m) To (m) Interval (m) Cu% Ag g/t Pb% Zn% 3.00 4.60 1.60 0.08 19.10 1.39 0.02 16.13 25.60 9.50 0.67 36.24 Incl. 19.02 5.06 6.00 0.81 46.32 56.75 65.0 8.3 0.01 1.05 0.13 0.2 Incl.
58.0 61.0 3.0 0.02 1.31 0.15 0.32 69.13 70.3 1.2 1.02 57.3 73.0 10.8 21.8 1.04 52.26 Incl. 74.0 76.1 2.1 1.23 69.29 and 79.0 85.0 6.0 2.56 128.16 Incl. 82.0 83.6 1.6 6.55 319.75 and 103.7 106.0 2.3 1.15 52.26 and 110.0 110.8 0.8 1.68 89.0. The deposit geometry observed in DD042 comprising an upper Pb-Zn rich silica-sulphide breccia and lower Cu-Ag rich chalcocite-clay lens is consistent with that observed and recently reported for holes in Lens 2 and suggests the mineralisation intersected here could potentially represent the southern extension of the Lens 2 mineralisation discovered beneath the Mostaza mine.
Consequently, in-fill drilling designed to potentially connect the Lens 2 mineralisation between these two centres will be a focus of the Phase IV programme. The results of hole DD042 suggest that the mineralisation may be coalescing and/or thickening to the south. This "pinch and swell" geometry, with alternating thick "lodes" separated by narrow "pinch-outs" is not uncommon for structurally-controlled ore deposits.
Importantly, the mineralisation remains open and untested to the south under shallow cover. This area will also be targeted with step-out drilling in the Phase IV campaign. The reported trend of significant Cu-Ag mineralisation intersected in drilling now measures over 400m in strike length, from the northern edge of the Mostaza mine to the intercept in hole DD042.
This lies within the broader 2.5km trend of surface alteration and mineralisation (Mostaza Fault Zone) extending from Lens 1 to the south and defined by mapping, rock chip geochemistry and IP geophysics surveys.
