The Cangrejos and Gran Bestia deposits are gold-copper, silica-saturated, alkalic porphyry-style deposits. This type of deposit is found along paleo-subduction margins (Carter, 1981; Cox et al., 1987).

Gold-copper mineralization is associated with sulfides that occur as open-space breccia fill or as disseminations in former mafic phenocrysts. Total sulfide content is generally less than 5% and consists of chalcopyrite and pyrite with minor bornite, molybdenite and pyrrhotite. In drill hole C17-65, native copper is found on fracture surfaces at depths ranging from 142 m to 186 m. This is not very common and is probably due to strong oxidation along a fracture zone.

The highest gold grades occur in calcic-sodic altered breccias at contacts between the porphyritic quartz diorite (PQD) and the metamorphic complex. The best gold grades occur in breccias where the dominant clast type is equigranular quartz diorite (EQD). The EQD is more mafic in composition, and gold is preferentially deposited in reducing (mafic) environments.

Cangrejos Zone
Current understanding of the surface geology of the Cangrejos Zone is limited because of a lack of outcrop exposures. An east-northeasterly trending porphyritic quartz diorite (PQD) intrudes quartz diorites (EQD) and schists (SCH) of the metamorphic complex. The southeastern contact is steep, but the northwestern contact dips approximately 50° to the southeast and is defined by porphyry dikes. The edges ........

The Cangrejos Project consists of two adjacent open pit mines referred to as 1) Cangrejos (eastern pit) and 2) Gran Bestia (western pit). Both pits will be mined with conventional hard rock open pit mining methods. The terrain is very steep with evergreen montane secondary forest, saprolite, and saprock overlying both pit areas. Dealing with the saprolite and saprock presents challenges for mine operations. This was anticipated during the development of the mine production schedule and in selecting the mine equipment.

The mine delivers 40,000 tpd of feed to the plant beginning in mid-year one through year five. The production ramps up during year six so the mine delivers 80,000 tpd of mill feed in years 7 to 25. IMC developed the production schedules by rock types of saprolite, saprock, partially oxidized, and fresh rock.

The preproduction period begins after the road between the site facilities and the crusher site is completed. The initial five months are for access pioneering only. Additional pioneering continues throughout the period of preproduction mining.

Waste material was reported by the rock types of saprolite, saprock, partially oxidized, and fresh rock. During the first five years of the mine life, the saprolite and saprock are delivered to the saprolite storage facility (SSF) located south-southeast of the Cangrejos pit. The SSF is constructed in four stages.

The fresh rock waste is delivered to the waste rock storag ........

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