The deposit at Amancaya is an epithermal gold and silver deposit, hosted in a steeply dipping structurally controlled quartz vein. Gold mineralization comprises disseminations of native gold and silver, electrum, silver sulphosalts, and accessory sphalerite, galena, chalcopyrite, and pyrite occurring with quartz, adularia, carbonates, clay minerals, limonite, and manganese oxides. These minerals were deposited from boiling of dilute saline fluids circulating in a hydrothermal system driven by the Eocene to Paleocene magmatism. The hydrothermal vein systems are considered a low sulphidation type based on their metal content and the volcanotectonic setting.

The most relevant mineralization from an exploratory point of view corresponds to the low sulphidation epithermal veins rich in gold and silver. These structures are distributed to the east of the La Peineta Fault System, along a north-south corridor of approximately two kilometres by eight kilometres (Central Veta Sector and Rosario del Llano Mine). They are mostly housed in the basal units of Paleocene (Chile-Alemania Formation, e.g., Amancaya Breccia).

In the Cerro Morros Blancos sector towards the southeast of the Central Vein, there is an area of advanced argillic type alteration that affects the basal units of the Paleocene. This sector is characterized by the presence of fault breccias with alunite and kaolinite, and subhorizontal silicified layers.

To the west of the Peineta Fault system there is mineralization of which the most important is the gold-copper veins of the Amancaya West sector. The veins strike north-south, 020° and 330° possibly associated with a porphyritic system of the Upper Cretaceous. In this sector, moreover, manifestations of IOCG mineralization linked to the Fm. La Negra, have been found.

Finally, thick quartz epithermal veins with iron and copper oxides are recognized in the sector Northwest sector, embedded in Devonian and Triassic units (Las Tórtolas formation and Agua Verde Granodiorite).

All of the veins that occur at Amancaya can be subdivided into two groups according to host units.
• Veins hosted in dacite-andesite domes (Central, Griega, Inesperada, and Cerro Amarillo).
• Veins hosted by breccias, tuffs, and volcanoclastic rocks (Rosario del Llano, Janita, Rosa, Nueva, and Julia etc.).

The main veins have been grouped within the Southern Block (Veta Central, Veta Griega, Veta Julia), and North Block (Veta Janita, Veta Nueva, Veta Rosa, Veta Laureana, Rosario del Llano, etc.).

The open pit mine will be carried out as a conventional operation using 30 t trucks and a combination of excavators and front-end loaders. Waste and ore will be blasted and mined separately using a “trenching” method to reduce the amount of dilution. A three metre wide trench will be blasted resulting in a 4.5 m wide trench after overbreak is taken into account. This waste material will be mined out from the trench using the excavator. Once the trench has been cleaned out, the vein will be blasted into the open slot and subsequently mined out using an excavator. The remaining waste on the mining bench will be blasted and mined out using front-end loaders.

The Amancaya Mine underground Mineral Reserves were estimated based on stope designs applied against the Mineral Resource block models for the Central Vein deposit. Planned and unplanned dilution are included in the stope shapes which have been designed for a sub-level stoping mining method.

The Amancaya ore is being trucked to the new plant at Guanaco for processing where it is being stockpiled until the new agitation leach plant is fully commissioned.

The new construction includes:
• Reversing conveyor to feed either the heap leach operation or the milling circuit
• Covered stockpile
• Single stage ball milling circuit operated in closed circuit with hydro-cyclones
• Pre-leach thickener
• Three-stage agitated leach circuit
• Three-stage counter-current-decantation (CCD) wash circuit
• Filter feed tank and plate and frame pressure filters to recover solution and produce filtered tailings
• Loading with front end loader and truck haulage to dry tailings deposit
• Dry tailings deposit
• Refurbished Merrill-Crowe circuit for precious metal recovery including:
• Clarifying filters
• De-aeration tower
• Zinc cementation (i.e., precipitation)
• Precipitate filters.

The Merrill-Crowe plant is an existing plant that was refurbished for use in the new milling circuit. Since ore from Amancaya contains higher concentrations of silver than the ore from Guanaco, Merrill-Crowe is preferred over activated carbon as the precious metal recovery process. Pregnant solution is pumped through clarifying filters where suspended solids are removed from the solution and on to the de-aeration tower. The de-aeration tower is a packed column that is operated under vacuum to remove oxygen from the solution in order to enhance the zinc cementation (commonly called precipitation) process. Zinc dust is added to the clarified, de-aerated solution where the gold and silver ions are reduced to form solid metal “precipitate”. The solids are removed from the solution with plate and frame filter presses. The filter presses will be cleaned manually on a batch basis. The dewatered precipitate will then be dried, mixed with fluxes, and smelted in the existing refinery. Barren solution from the Merrill-Crowe circuit is re-used as wash water in the CCD circuit.