Nexa Resources S.A. owns a total of 83.48% in the Magistral Property that corresponds to the sum of Nexa’s direct interest in Nexa Perú (0.18%) and Nexa’s indirect interest in Nexa Perú (83.37%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.92%). Nexa Perú holds 15 of the 36 mineral concessions and Compañia Magistral S.A.C, a company which according to Nexa is 100% controlled directly or indirectly by Nexa Perú, holds 21 of the 36 mineral concessions.
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Summary:
The Magistral deposit is a calc-alkaline, copper-molybdenum, porphyry deposit with a well developed envelope of copper-(molybdenum) mineralized skarn (Ristorcelli et al., 2008).
There are three types of mineralization at the Project:
• Skarn: The skarn mineralization is of highest grade, forming a hundred-metre scale rim within the country rocks around the porphyries. Garnet (grossular at proximal and andradite at distal alterations), epidote, chlorite, hematite, magnetite, quartz and inosilicate minerals (pyroxene and amphibole) form the skarn gangue mineralogical assemblage. Centimetre-scale mineralized veinlets and massive patches of sulphide (chalcopyrite, pyrrhotite, pyrite, and minor molybdenite) crosscut the skarn gangue assemblage.
• Mixed zone: It consists of a metre-scale interlayering between the skarn and the porphyry style mineralization. It is possibly formed by the combination of exoskarn, endoskarn, and also intrusive fingers (porphyry), making a complex and variable sort of mineralization that combines mineralogical and grade characteristics of skarn and porphyry mineralization.
• Porphyry: The porphyry mineralization is of lowest grade and is formed by several quartz, chalcopyrite, and molybdenite veinlets (“D”, “B”, and “A”-type veinlets), which constitute a final stockwork framework that crosscuts the intrusive porphyry. The skarn mineralization seems to be preferentially elongated and anisotropic parallel to the strata bedding of country rocks (limestone), whereas the porphyry mineralization envelope is coincident with the limits of the San Ernesto and H porphyry intrusives, whose texture, grade, and mineralogy are apparently more isotropic than those of skarn mineralization.
The skarn mineralization seems to be preferentially elongated and anisotropic parallel to the strata bedding of country rocks (limestone), whereas the porphyry mineralization envelope is coincident with the limits of the San Ernesto and H porphyry intrusives, whose texture, grade, and mineralogy are apparently more isotropic than those of skarn mineralization.