The Yauli unit region shows mineralization related to polymetallic epithermal systems, replacement bodies and polymetallic vein systems, as well as porphyry mineralization and skarns, thus indicating the great potential of the area. The southern portion of the Yauli Dome is including the San Cristobal polymetallic deposit. The San Cristobal-Andaychagua mining district includes only mantos and veins. The mantos are hosted by the Pucara limestone along the contact with the underlying Mitu Group, and occur mainly along the western flank of the Domo de Yauli. The veins are steeply dipping and crosscut rocks of the Mitu and Excelsior Groups, and locally the Chumpe and San Cristobal intrusions. Andaychagua Vein is one of the producers in the San Cristobal district, is one of the most important veins on the southeast side of the Chumpe intrusive. The vein lies on the northeast side of the Chumpe Anticline. About three and a half kilometers southeast of the San Cristobal Vein system. The Andaychagma Vein strikes N 30° E and dips 85° northwest. The vein can be traced on the surface for about four kilometers, three of which are in Mitu volcanic rocks and one of which in Excelsior Phyllites. The structure continues on the surface across the axial zone to the southwest side of the Chumpe Anticline, but only as a fault structure without apparent mineralization. The Andaychagua Vein carries sphalerite, galena, and silver minerals.

(Translated from Spanish by Google Translate) The Andaychagua underground mine is part of Yauli operating unit. The Andaychagua mine is exploiting the Andaychagua vein using the Cut and Fill method. The mining cycle begins with drilling and blasting, extraction, sustaining and ends with the retreating cemented filling could demand up to 3 months time for a mining panel up to 200 m. During 2022, the mining designs have been optimized, managing to increase by 40% the height of the benches in Salvadora, Salvadora Norte and Prosperidad Techo of the Andaychagua unit. Regarding 2021, an increase in the Zn head grade was achieved by 6% and a reduction in the Pb head grades by 1% and Ag by 12%, this was due to the increase in Zn grade by contribution of the Salvadora Norte body and the decrease in the Ag grade by the withdrawal of the Puca Urco vein reserves from the budget. In 2022 ore production was down 13% from 2021. The exploration program allowed the incorporation of new economic mineral resources in the Bárbara vein and in the extensions of the Salvadora, Prosperidad Techo, Andaychagua and Adriana bodies. Satisfactory results were obtained, with high metallic contents of Zn, Pb, Cu and Ag.

Andaychagua's processing plant include grinding circuit consist of primary ball mills #1, 2 (10.5 'x 14', 8 'x 10') and secondary grinding ball mill (7’ x 12’).

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