The Mirador deposit is a multiphase porphyry Cu Au-Mo system, within which four intrusive pulses dated by the U-Pb zircon method at 41.3 + 0.4 to 38.4 + 0.7 Ma are currently recognized. These are: feldspar- and biotite-bearing granodioritic Mirador porphyry; dacite porphyry with biotite and quartz eyes; porphyritic granodiorite stock; and late dacite porphyry. The deposit occurs within the Domeyko fault system but is localized by a N65-80°W-trending fault, suggesting the possibility of a new structural system with potential to host porphyry copper deposits in the Centinela district. The porphyry system is emplaced into Jurassic calcareous shale and gypsum, giving rise to peripheral, locally mineralized skarn.

Four mineralization types are recognized: early porphyry Cu-Au with potassic alteration, EB, A and B veinlets, and hypogene chalcopyrite bornite-Au mineralization; Granodiorite stock with Cu-Mo mineralization, sericite-chlorite alteration, fine-grained disseminated sulfides and abundant molybdenite; Cu-Au-bearing garnet skarn with chalcopyrite-pyrite-magnetite; and hornfels and skarn displaying in situ oxidation, which is affected by gravitational collapse due to basal gypsum dissolution. Piedmont gravel and tectonic and solution-collapse breccias then channeled supergene copper-bearing solutions, leading to precipitation of chrysocolla, antofagastite and copper wad. The resultant high grade oxide copper ore is currently being exploited by Minera Centinela.

Centinela mines sulphide and oxide deposits 1,350 km north of Santiago in the Antofagasta Region, one of Chile’s most important mining areas.

Centinela consists of Centinela Concentrates (Esperanza + Esperanza Sur and Encuentro Sulphide mostly sulphide porphyry deposits) and Centinela Cathodes (Tesoro Central and Tesoro Sur oxide deposits, including the oxide portion of the Mirador, Encuentro and Llano deposits).

Esperanza Sur is 4 km south of the Esperanza pit and is close to Centinela’s concentrator plant. The deposit contains 1.4 billion tonnes of reserves with a grade of 0.4% copper, 0.13 g/t of gold and 0.012% of molybdenum. Stripping advanced in 2021 and is expected to be completed in the first half of 2022.

Minning operations is carried out via conventional truck and shovel drill and blast method. Of all Centinela consumes the most diesel, operating some 120 mine haulage trucks and mining from six open pits.

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