MINSUR S.A. through its subsidiary Cumbres Andinas S.A., owns 60% of the shares of Cumbres Andinas S.A.C., which owns 99% of Marcobre S.A.C. The latter, operates Mina Justa copper mine.
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Summary:
The Project is located in the plain of the Central Coast of Peru. The region is located east of one of the most active plate borders, that is part of the Ring of Fire, and where a large number of destructive earthquakes have been recorded.
The deposit is an “iron-oxide-copper-gold” (IOGC) type breccia deposit with a combination of sulphides and oxides. Feed material consists of primary sulphide material (bornite, chalcopyrite and pyrite), secondary sulphides (bornite, chalcocite, digenite and minor traces of covellite) and primary transitional ore (bornite as well as cuprite, atacamite, native copper and silver). The distribution statistics for each of the key variables are graphically displayed CuAS, CuCN, and CuR.
The ore deposit has a strong structural control; it is delimited between the regional faults Lechuza, Tunga, and Treinta Libras, with Andean strike (SE-NW), and normal-dextral displacement. Among these faults, there is a fault and fracture system with SW-NE strike, with a preferred dip to southeast, known as the Mina Justa fault system. These structures are usually of reverse type, with medium to low or up to subhorizontal angles, and their displacement ranging from a few centimeters to some tens of meters. Mineralized bodies (Main and Upper mantles) are interrupted by longitudinal faults parallel to the Lechuza and Tunga faults (Huaca fault system), which generate dislocations on said mineralized bodies.
Iron mineralization in the Marcona zone has a pattern of iron oxides copper-gold mantles. It comprises two deposits named Mina Justa and Manto Magnetita Oeste (Western Magnetite Mantle) that are placed in the Río Grade volcanic-sedimentary formation of the Upper Jurassic, which includes mainly andesitic lavas and pyroclastic flows, with thin interbedded arch sandstone and siltstone sequences. Large extensions of sulfide bodies and some oxide lenses have been subject to an intense hydrothermal alteration, which basically consisted of secondary iron oxides, actinolite, and chlorite, with albite, potassium feldspar, apatite, scapolite, and calcite. The economic mineralization of the Mina Justa deposit is closer to the surface to the north and west of the deposit, and reaches a depth of 550 m below the surface southeast of the deposit, the prevailing sulfides consist of bornite and chalcocite in the upper area of the ore deposit, and chalcopyrite in the lower part. On the other side, copper oxides characterize the mineralization of the Manto Magnetita Oeste deposit. Figure RE-10 shows the Project geological characteristics.
The Mina Justa ore deposit is composed of the Mina Justa (Main) and Manto Magnetita ore deposits, which are located in the volcanic sedimentary formation Río Grande of the Upper Jurassic. This ore deposit has a strong structural control and is mainly delimited by regional faults of Andean strike (SE-NW).
This ore deposit is a hydrothermal deposit of iron - copper - gold oxide type. The Mina Justa ore deposit extends over an oval area comprised of 2.1 km x 1.5 km with a depth of up to 150 m; while the Manto Magnetita ore deposit of copper oxides, has a tubular shape of 700 m x 350 m and 25 m and 35 m thick.