The Bolivar deposit is classified as a high-grade Cu-Zn skarn and exhibits many characteristics common to this deposit type (Meinert, 2007). The term skarn refers to coarse-grained calcium or magnesian silicate alteration formed at relatively high temperatures by the replacement of the original rock, which is often carbonate-rich.

Skarn alteration and mineralization at the Bolivar property is hosted primarily in a package of sedimentary rocks that occur as a layer or lens within the LVS (Reynolds, 2008). All sedimentary units have undergone low grade metamorphism. The lowermost sedimentary horizon observed is a dolostone which ranges from 24 m to 40 m in thickness. The lower part of the dolostone horizon is interlayered with siltstone. To the south, progressively less of the sedimentary sequence is cut out by granodioritic intrusive rocks and the dolostone is observed to be underlain by a siltstone horizon. The lower siltstone unconformably overlies the LVS. The dolostone is overlain by a discrete layer of siltstone. The average thickness of this siltstone unit is 12 to 30 m. Horizons of argillaceous dolostone (50 m thick) and argillaceous limestone (9 m thick) are above the siltstone marker layer. The uppermost sedimentary horizon is a limestone with local chert and argillaceous laminations. The vertical thickness of this horizon varies considerably in cross-section (108 to 173 m) and this variation is attributed to paleo-topographic relief. The upper contact ........

The Bolivar Mine is currently mined by the sub-level stoping and room and pillar methods and the specific method applied to a particular area of the mine is determined by geotechnical constraints, mineralization trends, dimensions and mine production targets.

Current production at Bolivar comes from the El Gallo Inferior, Chimenea 1 and 2 and the Bolivar West mineralized zones. Mineralized material is currently hauled to the surface using one of several adits or declines accessing the mineralized zones and is then dumped onto small pads outside the portals. The mineralized material is then loaded into rigid-frame, over-the-road trucks and hauled on a gravel road approximately 5.1 km south to the Piedras Verdes Mill. As explained in more detail in Section 18, the mine is constructing an underground tunnel that will enable mineralized material to be delivered via underground truck transport to a portal adjacent to the Mill.

Sub-Level Stoping - Bolivar West
The longhole method is applied in the shallow dipping mineralized bodies in Bolivar West. Excavation for longholes with openings of 9.0 m and pillars of 7.0 m x 7.0 m for stope heights between 12.0 m and 15.0 m. From the access ramp, access to the mineralized material is established in the central part of the chamber and the mineral cut begins. A drive is developed within the mineralized material, then the drilling of long holes is carried out and extraction begins. Ramps are established in some cas ........

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The Piedras Verdes Plant, located 5.1 kilometers from the Bolivar Mine, uses a conventional crushing-grinding-flotation circuit to recover mineralized mineral and to produce commercial quality copper concentrates with silver and gold by-product credits.

Bolivar’s Piedras Verdes processing facilities started operating in October 2011 at 1,000 tpd of nominal throughput. The ore processing capacity was expanded to 2,000 tpd in mid-2013. The mill has been upgraded since and the current nominal throughput capacity is 3,500 tpd although the mine has exceeded this throughput on many occasions and in 2020 has achieved 5,000 tpd.

Piedras Verdes operates a conventional concentration plant consisting of crushing, grinding, flotation, thickening of concentrates, filtration of concentrates, and tailings disposal.

The operation is completely manual with no automation or online monitoring being used in the processing circuit. The grinding product, or flotation feed pa ........