The Atacocha property is situated in the Pasco region of the Western Cordillera of the Andes mountain range in central Peru, within the Eocene-Miocene Polymetallic, and Miocene Au-Ag Epithermal Belts.

Within the property area the stratigraphic units of primary interest are the Chambara´ Aramachay and Condorsinga formations, as well as other undifferentiated limestone units of the Pucara´ Group, the Goyllarisquizga formation, and stratigraphically overlying basalt layers. Intrusive rocks within the property are variably porphyritic dacite to quartz diorite with hornblende and biotite phenocrysts. Dacitic dikes are sub-divided into 2 units: porphyritic with feldspar phenocrysts and little quartz restricted to the groundmass; and porphyritic with abundant quartz phenocrysts, with minor biotite and hornblende. These dacitic dikes generally trend north-south, and are observed in 3 areas: Santa Ba´rbara/central, south along/parallel to the Atacocha Fault, and south of Section 3. The intrusive suite is part of the Milpo-Atacocha-Vinchos, age dated to 29-26 Ma. The Santa Ba´rbara and San Gerardo stocks are two principal intrusive units within the property.

At Atacocha, mineralization is characterized as either a skarn-, replacement- or hydrothermal vein/brecciastyle mineralization. Skarn-related mineralization generally spatially associated with either the Santa Barbara stock or San Gerardo stock is paragenetically earlier, followed by the hydrothermal minerali ........

Atacocha operates two mines: the Atacocha underground mine and the San Gerardo open pit mine. The underground mine is currently suspended, but mining continues in the San Gerardo open pit mine.

San Gerardo is an open pit operation located at the top of mineralized zone, and is mined by 6 m high benches. Since the temporally suspension of Atacocha underground mine, the open pit production is responsible by the metallurgical plant feed. Operations are carried out by contractor with a mining fleet that allows selectivity in the loading process.

The Atacocha underground mine is mined by the overhand Cut & Fill (C&F) and sublevel stoping (SLS) mining methods. C&F stopes are 20 m high consisting of 4 m high cuts and a minimum mining width of 4 m. C&F stopes are located 55 m from the main ramps and accessed by stope access ramps with grades varying from -15% to +15%. Production is achieved by horizontal drill and blast, and backfilled using unconsolidated waste fill or hydraulic backfill. The SLS mining method has demonstrated increased productivities and reduced unit costs as compared to the C&F mining method. SLS stopes are located a minimum of 40m from infrastructure, are 20 m high, 30 m long and have a minimum mining width of 4 m. Production is achieved by vertical blastholes, and backfilled using unconsolidated waste fill.

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The Atacocha concentrator utilizes a conventional crushing, grinding, and sequential flotation scheme to produce lead and zinc concentrates with an average daily processing rate of approximately 4,300 tonnes. A flashflotation step is included in the grinding circuit that recovers lead at a grade sufficiently high to report directly to the final lead concentrate. The majority of gold and silver report are into the lead concentrate. Despite the plant having capacity to produce copper concentrate, the circuit of the plant has been disabled and the Atacocha metallurgical plant produces only zinc and lead concentrates.

Description (2017)
The first flotation circuit collects a bulk lead/copper concentrate that is then subject to differential flotation to collect lead minerals as concentrate and copper minerals as tails, finally each stream is individually cleaned in multiple flotation stages to produce final concentrates that are stored in their respective thickeners.
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