The Quellaveco deposit is porphyry copper-molybdenum orebody with an elongated mineralised zone. Primary sulphide mineralisation dominates the deposit and is successively overlain by a secondary supergene copper mineralisation blanket. This is followed by low grade copper-bearing oxides that are capped by barren ignimbrites. At least five stages of intrusion are recognised; the oldest intrusives correspond to regional granodiorite surrounding the main orebody. Three syn-mineralisation intrusions of monzonitic to dacitic composition host most of the mineralisation. All of these are cut by a suite of late post-mineral intrusives. The Quellaveco deposit, located near the northern end of the Paleocene to early Eocene porphyry copper belt of the central Andes (Sillitoe, 1988; Clark et al., 1990), is centered on a multiphase quartz monzonite porphyry stock emplaced into an equigranular granodiorite pluton, which itself cuts rhyolitic volcanic rocks assigned to the Late Cretaceous to early Paleocene Toquepala Group (Estrada, 1975; Guerrero and Candiotti, 1979; Candiotti, 1995). The pluton, which crops out over >3 km2 in the vicinity of the Quellaveco stock, as well as extending northward beneath postmineral ignimbrite and gravel cover, is part of the granodioritic to monzogranitic Yarabamba superunit of the Coastal batholith (Pitcher, 1985). Phenocrysts in the porphyries are made up of abundant plagioclase, quartz, and biotite, plus scattered K-feldspar and hornblende, all surrou ........

Mining from the Quellaveco deposit will involve excavation of a huge open-pit. The final pit dimensions are anticipated to be: approximately 3000m (N-S) by 1700m (E-W), and 930m deep.

Mining of the ore body by open pit methods will require diversion of the Asana River around the Quellaveco deposit via a canal and tunnel system 7.2 km long, returning the flow downstream of the proposed waste rock disposal area.

Excavation of the pit will produce more than a million tons of waste rock, which will be deposited in the Asana River riverbed, downgradient of the open pit and the subsequent pit lake. Waste rock piles will reach an average height of 320m.

After mine closure, the pit will fill with water forming a lake with a maximum depth of about 384m.

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