The Guanaco-Amancaya Operation is located in the Central Depression of northern Chile, which is a north-northeast striking Paleocene to early Eocene morphostructure formed as part of a volcanic arc under extensional and/or transtensional conditions. The structure extends for 3,000 km, is composed of mafic to felsic volcanic rocks of calc-alkaline affinity, typically affected by extensive alteration, and has gabbroic to dacitic intrusive and subvolcanic bodies emplaced over its length. These rocks are grouped into the Cinchado (north) and Chile-Alemania (south) formations that lie unconformably over Cretaceous volcanic rocks. During the middle Eocene, the change of convergence angle and the acceleration of subduction resulted in crustal thickening, eastward migration of the volcanic arc, and the onset of the Incaic orogeny, which uplifted the Incaic Range and produced giant middle to late Eocene copper porphyry deposits to the east.

The Guanaco deposits are considered examples of structurally controlled high-sulphidation epithermal systems.

The most important structural features related to gold mineralization at Guanaco follow east-west and east-northeast to west-southwest trends. Gold bearing structures are all steeply inclined ledges (veins) composed of massive vuggy and cryptocrystalline quartz of replacement origin. Individual ledges are up to five metres wide, however, more commonly they appear to comprise several impersistent siliceous strands sep ........

The Guanaco-Amancaya Operation consists of the Guanaco Mine (Guanaco) and Inesperada satellite deposit (Inesperada), the Amancaya Mine (Amancaya), and the Guanaco heap leach pads (Heap Reprocessing project).

Mining at Guanaco was discontinued in February 2020. Amancaya is currently in production.

The LOM plan for the Guanaco-Amancaya Operation extends over 12 years. Amancaya continues operating throughout 2022, however, output tapers off in 2023 as operations wind down. Open-pit mining at Inesperada starts in 2023 when Amancaya's Mineral Reserves are exhausted. The pit operates until its reserves run out at the end of 2025. Heap Reprocessing begins in 2023 and continues through to 2033. The heaps will be reprocessed in reverse order of their numbering, starting with Heap III. Heap II comes on stream in 2027, near the end of Heap III's production. Leaching of Heap I begins in 2030 and continues to the end of the mine life in 2033.

Amancaya
The mining method at Amancaya is sublevel open stoping (SLS). The mine has a 15 m sublevel interval, and the production drifts have a 4.0 m wide by 4.2 m high profile. An ore horizon between sublevels is developed by driving crosscuts to the deposit and advancing ore drives along the vein at the upper and lower sublevels. The vein between the upper and lower ore drives is drilled with longholes and blasted in benches. In the first inter-sublevel horizon, the longholes can be drilled as upholes or downh ........

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