The Yauricocha Mine features several mineralized bodies, which have been emplaced along structural trends, with the mineralization itself related to replacement of limestones by hydrothermal fluids related to nearby intrusions. The mineralization varies widely in morphology, from large, relatively wide, tabular manto-style deposits to narrow, sub-vertical chimneys. The mineralization features economic grades of Ag, Cu, Pb and Zn, with local Au to a lesser degree. The majority of the deposits are related to the regional high-angle NW-trending Yauricocha fault or the NE-trending and less well-defined Cachi-Cachi structural trend. The mineralization generally presents as polymetallic sulfides but is locally oxidized to significant depths or related to more Cu-rich bodies.

Goyllarisquizga Formation
The oldest rocks exposed in the area are the lower Cretaceous Goyllarisquizga arenites. This formation is approximately 300 m thick and comprises thick gray and white arenites, locally banded with carbonaceous lutites as well as small mantos of low-quality coal beds and clay. In the vicinity of Chaucha, these arenites have near their base interbedded, red lutite. The arenites crop out in the cores of the anticlines southwest of Yauricocha, as beds dispersed along the Chacras uplift, and isolated outcrops in the Éxito zone.

Jumasha Formation
The mid-Cretaceous Jumasha Formation consists of massive gray limestone, averages 700 m thick, and concordantly overlies the Goyllarisquizga Formation. Intercalations of carbonaceous lutites occur at its base near the contact with the arenites. These layers are succeeded by discontinuous lenses of maroon and grey limestone, occasionally with horizons of lutite and chert about 6 m thick. Also present are pseudo-breccias of probable sedimentary origin and a basaltic sill.

Celendín Formation
The Celendín Formation concordantly overlies the Jumasha Formation and contains finely stratified silicic lutites with intercalations of recrystallized limestone of Santoniana age as well as the France Chert. The average thickness in the Yauricocha area is 400 m.

Casapalca Red Beds
The Casapalca red beds lay concordantly on the Celendín Formation with a gradational contact. It has been assigned an age between upper Cretaceous and lower Tertiary, but because of the absence of fossils its age cannot be precisely determined. It is composed primarily of calcareous red lutites, pure limestones, and reddish arenaceous limestone. Lava flows and tuffaceous beds have been occasionally reported.

Mineralization at the Yauricocha Mine is represented by variably oxidized portions of a multiplephase polymetallic system with at least two stages of mineralization, demonstrated by sulfide veins cutting brecciated polymetallic sulfide mineralized bodies. The mineralized bodies and quartzsulfide veins appear to be intimately related and form a very important structural/mineralogical assemblage in the Yauricocha mineral deposit. Comments made herein regarding the characteristics of the Yauricocha district apply directly to the Yauricocha Mine.

Mineralization in the Yauricocha district is spatially and genetically related to the Yauricocha stock, a composite intrusive body of granodioritic to quartz monzonitic composition that has been radiometrically dated at late Miocene (approximately 7.5 million years old) (Giletti and Day, 1968). The stock intrudes tightly folded beds of the late Cretaceous Jumasha and Celendín Formations and the overlying Casapalca Formation (latest Cretaceous and Paleocene?). Mineralized bodies are dominantly high-temperature polymetallic sulfide bodies that replaced limestone. Metal-bearing solutions of the Yauricocha magmatic-hydrothermal system were highly reactive and intensely attacked the carbonate wall rock of the Jumasha and Celendín Formations, producing the channels in which sulfides were deposited.

The mine production areas are grouped into six mining areas: Mina Central, Esperanza, Mascota, Cuye, Cachi-Cachi, and Cuerpos Pequeños. Sub-level caving is the primary mining method at Yauricocha representing 84% of the production. This method is in use Mina Central, Esperanza, Mascota, and Cuye. Sub-level caving and overhand cut and fill is used for Cachi-Cachi, and overhand cut and fill is used for Cuerpos Pequenos.

Sub-level caving is comprised of three sub-levels that are established for each 50 m level resulting in a planned 16.7 m between sub-levels labeled as pisos (floors). Material is caved from the sublevels and recovered in a drawpoint. Drawpoints from the footwall into the ore are typically 3.5 m wide x 3.0 m high and are spaced 8.0 m apart. Steel sets, shotcrete and bolting are used as ground support in the drawpoints and the length of each drawpoint varies with the thickness of the orebody. As the drawpoint is developed, ore samples are collected for grade control analysis from the left and right ribs. Upholes are drilled in stopes to initiate caving. Effective draw control is an important to successful extraction for this mining method. Drawpoints are staggered by 4.0 m from sub-level to sub-level.

Cut and fill mining is employed in the smaller orebodies. Typically, the cuts are mined 2.0 m wide x 3.0 m high in an overhand (ascending) technique where the lower levels are filled as mining progresses to the next sub-level above. Sill pillars are left between levels as mining comes up underneath the previously mined level. Based on geotechnical constraints the sill pillars are typically a minimum of 3.0 m in thickness.

Polymetallic sulfide ore accounts for more than 99% of the material mined at Yauricocha. Material classified as lead oxide can also be encountered, but it is a minor component of the overall tonnages in the reserves estimate.

The mine is accessed by two shafts, Central Shaft and Mascota Shaft, and the Klepetko and Yauricocha tunnels. Ore and waste are transported via the Klepetko Tunnel at the 720 level (elevation 4,165 masl) which runs east-northeast from the mine towards the mill and concentrator, and the 4.7 km Yauricocha Tunnel, commissioned in 2018, that also accesses the mine at the 720 level. The Yauricocha Tunnel was added to increase haulage capacity and serves as a ventilation conduit.

The Yauricocha Shaft, currently under construction, will provide access down to 1370 level and is expected to be in operational in 2022.

Mine production at Yauricocha is currently an average of 3,300 t/d with planned annual production of 1.2 million tonnes per year (Mt/y) for 6 years.

Mine trucks deliver polymetallic mineralized material and oxide mineralized material to their respective coarse mineralized material bins. The single crushing plant batches mineralized material that is delivered to dedicated mineralized material bins to each processing line. Each process line includes a grinding stage.

Ore is processed at the on-site Chumpe plant using a combination of crushing, grinding and flotation and is permitted to produce at a rate of 3,150 tpd, which we expect to increase to 3,600 tpd during 2020 upon receipt of the ITS permit.

Yauricocha operates a conventional concentration process that includes two parallel circuits to process polymetallic ore and oxide ore. Each circuit consists of a crushing stage, grinding, sequential differential flotation, dewatering of the concentrates, thickening and disposal of the flotation tails. The Yauricocha plant currently produces three mineral concentrates: lead sulfide concentrate, copper sulfide concentrate, and zinc concentrate.

Yauricocha polymetallic circuit has a nominal capacity of 3,000 t/d. The polymetallic plant is showing a consistent upward trend in throughput capacity. During the January to October 2019 period, the polymetallic circuit operated on average at 2,926 t/d of fresh feed. Silver is preferential ........