The Colquijirca deposit (Tajo Norte) is structurally located within asymmetric synclines and anticlines, whose flanks are Principal-Mercedes-Chocayoc-La Llave-La Pampa; and stratigraphically located in the Calera Formation (Lower Tertiary-Eocene), middle and upper members. The base metal zone (Zn + Pb-Ag) is the outermost halo of mineralization (cordillera-type) and, by volume, the zone of greatest economic importance. Its mineralogy consists of sphalerite and galena as vein ores, which occur as fracture filling and cavities, disseminations, and massive replacements. The gangue consists of pyrite, specular hematite, magnetite, kaolin, barite, siderite, ankerite-dolomite, and fluorite, less commonly. All of them occur as fracture filling and cavities. Native silver as filigree in cavities, and in association with siderite, has been observed near the transition zone. It is also possible to observe the occurrence of chalcopyrite-galena-dickite as filling in fractures and replacement zones.

Tajo Norte is an open pit operation that exploits zinc-lead-silver ores.

It is a conventional truck and shovel operation, through a contractor. The height of a workbench is 6 m and the equipment used includes DM45 and DML drilling rigs. Loading are by hydraulic excavators EC950E (5.6 m3) and 374D (4.6 m3) and hauling is by G500 B8X4 trucks (24.5 m3). For 2021 we are planning to use 8 excavators and 48 trucks. To maximize mine production, Tajo Norte mine employs a fleet management system that supports the transmission and receipt of data across the mobile fleet, and supports the collection of data which is input directly by equipment operators.

The ore from Tajo Norte is treated at Plant 2, which uses the selective flotation process to achieve the concentration of the economic mineralization. It includes the crushing, washing, sorting, milling, conditioning, flotation, and filtering processes, as well as the respective tailings storage yards. Given the equipment characteristics and layout, the plant has the ability to beneficiate silver, lead, and zinc ores. It has direct access to a railway, which it uses to transport the concentrates to the port of El Callao.

Treatment capacity: The El Brocal processing plant has a total capacity of 20,000 MTD, which is shared by the ore from Marcapunta and Tajo Norte.