The Cerro de Pasco deposit is a complex epithermal polymetallic deposit with base and precious metal mineralization, mainly silver, characterized by vein, breccia-hosted, and carbonate-replacement mineralization. This deposit type has also been referred to as a “Cordilleran base- metal deposit” type (Baumgartner et al., 2008). The term “Cordilleran” was first applied to base metal-rich polymetallic vein deposits (Sawkins, 1972; Einaudi, 1982; Guilbert and Park, 1985; Bartos, 1987; Fontboté and Bendezú, 2009; Catchpole et al., 2015). Cordilleran deposits have also been referred to as Butte-type vein deposits (Meyer et al., 1968), polymetallic veins, and zoned base metal veins (Einaudi et al., 2003). Because the mineralization in many districts is dominantly mantos and not veins, and they commonly contain gold and silverin addition to base metals, Bendezú et al. (2008) and Fontboté and Bendezú (2009) prefer the more general term Cordilleran polymetallic deposits.

Rottier et al. (2018b) describe three successive mineralization stages at Cerro de Pasco resulting in epithermal low- to high-sulphidation mineral associations emplaced at a paleodepth from <500 m to 1,500 m in the shallow part of a porphyry system:

1) Pyrrhotite pipes grading outward to sphalerite and galena replacement bodies (Stage A).
2) Quartz-pyrite veins (Stage B1) and a funnel-shaped massive replacement body of pyrite-quartz (Stage B2) with quartz-sericite ± kaolinite alteration.

(Translated from Spanish by Google Translate)
The Cerro de Pasco Unit consists of two underground mines (Vinchos, Paragsha) and an open pit (Raúl Rojas). In 2012-2014 the open pit and underground mining operations wound down and processing shifted towards the treatment of old stockpiles which continues today.

Vinchos Mine (beginning of Operation 1975).
Vinchos mine is in under closure process since 2016.

Paragsha underground mine (beginning of Operation 1902).
The Paragsha mine has been temporary suspended since 2016. The infrastructure for the pumping system remains operational and in good condition.

In 2015, ore production came from mine sectors having higher ore grades and a greater volume of reserves. Due to the characteristics of the terrain, conventional semi-mechanized mining techniques were employed, including wood bracing and shoring as well as cemented hydraulic backfill.

Raúl Rojas open pit mine (beginning of Operation 1956).
The Raul Rojas mine has been temporary suspended since December 2015.

Since 2016, processing of marginal ore from the stockpiles mined at the Raul Rojas open pit in previous years begins.

Marginal ore stockpiled from the Raúl Rojas open pit mine is treated at the Paragsha-San Expedito.

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(Translated from Spanish by Google Translate)
Sulphide Concentrators - Paragsha/San Expedito

Throughout the 2017 year, operational changes were made to increase production and improve the metallurgy of concentrates. In the crushing area, the classification of the marginal with high humidity was optimized, making it possible to continue operations. In the third quarter of the year, the construction of the sorting circuit was completed and the testing process for the treatment of the marginal began in 2018. This, together with the optimization projects for secondary / tertiary crushing, grinding and flotation, will mean an improvement of the quality of the grades, better recoveries and a greater volume of concentrates.

During 2018, the crushing, grinding and filtering circuits of the Paragsha plant continued to be used, the San Expedito Pb circuit was transferred to the Paragsha plant and the Zn circuit was expanded in San Expedito.