The Cerro Corona copper-gold deposit is typical of porphyry style mineralisation comprising stock work quartz-pyrite-marcasite-chalcopyrite ± bornite ± hematite ± magnetite veining, hosted by intensely altered intrusive lithologies of diorite to dacitic composition.

The Cerro Corona copper-gold deposit is hosted by a 600 to 700 metre diameter sub-vertical, cylindrical-shaped diorite porphyry emplaced in mid-Cretaceous limestone, marls and siliciclastic rocks. Within the porphyry, the copper-gold mineralisation is primarily associated with zones of stock work quartz veining conforming to classic porphyry-type vein definition. The Cerro Corona porphyry is unusual in that it carries a very high gold content compared to other copper-gold deposits.

There are at least two phases of diorite placement, only one of which is mineralised. The non-mineralised diorite is generally regarded as the last event, and is referred to as ‘barren core’. Most recent geological modelling strongly suggests that the Cerro Corona porphyry probably comprises four or five satellite stocks, the last two of which are barren. Early mineralisation was accompanied by moderate to strong potassic alteration, which has been commonly overprinted by late, semi pervasive argillic alteration and locally, by structurally controlled phyllic alteration assemblages (quartz-sericite-pyrite).

There are three distinct mineralised zones within the deposit. These are identified as the annulus zone, the northern zone and the southern zone. Each of these is treated separately in geological and resource modelling.

In addition to the mineralised zones, the deposit is characterised by several domains conforming to the degree of oxidation and weathering. Supergene oxidation and leaching processes at Cerro Corona have led to the development of a weak to moderate copper enrichment blanket. This allows for the subdivision of the deposit from the surface downward, into an oxide zone, a mixed oxide sulphide zone, a secondary enriched (supergene) sulphide zone and a primary (hypogene) sulphide zone.

The Cerro Corona deposit is mined by conventional surface open pit mining methods. The final surface mine area is expected to cover some 950m by 1,050m. The mining operation will extend from the crest of the original Cerro Corona hill, which peaked at 3,964m amsl, to a final depth at around 3,460m amsl.

The current mining operation using open pit methods will be continued on a similar basis utilising a mining contractor. The material movement rate in the new LoM 2030 is variable over the mining schedule and therefore a mining contractor with the ability to mobilise and demobilise additional equipment and personnel offers advantages over an ownermining alternative. Mining benches are all 10m high and haul roads have a maximum gradient of 10%. All mined material requires drilling and blasting, utilising blast holes with a diameter of 200mm and applying variable powder factors according to rock hardness.

The processing plant reflects a typical copper flotation plant, with a design capacity of 6.9Mtpa. The crushing plant comprises two jaw crushers in parallel and two Abon Sizers in each line. Crushed product is conveyed to a two-stage grinding circuit consisting of a Semi Autogenous Grind (SAG) mill and a ball mill, in closed circuit with cyclone cluster for classification. Cyclone overflow represents the final milled product and feeds the flotation plant. The rougher flotation produces a bulk concentrate and final tails, which is then reground and sent to cleaner flotation. The cleaner tails go to scavenger flotation, while the concentrate, with a grade of over 20% copper, goes to the next process.

The final concentrate is thickened and filtered before being stockpiled for road transport (380km) to the Salaverry port, for shipment to copper smelters in Japan, Germany and Bulgaria. The thickened rougher flotation tails and the tails from the cleaner-scavenger flotation are sent by gravity to the TSF.