The Chinchillas and Pirquitas deposits are within the Bolivian tin-silver-zinc belt which occupies the back-arc portion of the central Andes and extends from the San Rafael tin-copper deposit in southern Peru to northern Argentina. The Bolivian tin-silver deposits are typically associated with felsic volcanic domes of broadly rhyodacitic composition (Cunningham et al., 1991). Bolivian-type Ag-Sn deposits generally consist of sulphide and quartz-sulphide vein systems typically containing cassiterite and a diverse suite of base and trace metals, including Ag in a complex assemblage of sulphide and sulfosalt minerals. The vein systems are generally spatially and likely genetically associated with epizonal (subvolcanic) quartz-bearing peraluminous intrusions one to two kilometres in diameter, although the mineralisation may be entirely hosted by the country rocks into which the intrusive stocks were emplaced. The Chinchillas deposit is modelled as a Tertiary-aged diatreme volcanic centre that has intruded Paleozoic sedimentary basement rocks. The mineralisation occurs mostly as disseminations, veinlets, and matrix fill.

Most of these deposits are characterised by the intrusion of dacite dome complexes with mineralisation hosted in shear zones and breccia within the dacite domes and/or within shear zones and breccia within the host rocks. At Pulacayo, Potosí and San Cristóbal, where associated domes are present, there is significant mineralisation within the domes. More ........

Open pit mining is carried out by MPSA as an owner mining operation with ore hauled from Chinchillas pit to the Pirquitas plant.

The Chinchillas deposit is located in the high lands of the Andes. The topography of the property consists of several mountains and hills on the sides of property with a small valley in the middle. The orebody is located mainly in the bottom of the valley with extensions stretching to the west on the hillside. The elevation varies from about 4,090 masl in the east side of the valley to 4,300 masl on the peaks in the west. There is a small creek in the middle of valley running from west to the east.

The Chinchillas deposit is mined as a conventional open pit operation. Most of the in-pit haulage for both ore and waste is carried out using 100 t haulage trucks. Ore is mined in five metre benches and stockpiled in a staging area close to the pit. From the staging area, ore is transported to the crusher at the Pirquitas Operation which is 42 km away from Chinchillas. Throughout the mining operation, low grade ore is stockpiled near the pit rim to be processed at the end of mine life. The mining operation is conducted by the owner. Ore haulage was changed to owner operated in 2021.

Waste rock is mined and hauled to two major on-site rock storage facilities based on geochemical characteristics. For the mine planning work the NSR is calculated for each block. No dilution is included in the block model. Ore is placed in the ........

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