The geology of the El Quevar project is characterized by silver-rich veins and disseminations in Tertiary volcanic rocks that are part of an eroded stratovolcano. Silver mineralization at El Quevar is hosted within a broad, generally east-west-trending structural zone and occurs as a series of north- dipping parallel sheeted vein zones, breccias and mineralized faults situated within an envelope of pervasively silicified brecciated volcanic rocks. There are at least three sub-parallel structures that extend for an aggregate length of approximately 6.5 kilometers. Several volcanic domes (small intrusive bodies) have been identified and mineralization is also found in breccias associated with these domes, especially where they are intersected by the structures. The silver mineralization at the Yaxtché zone is of epithermal origin. The cross-cutting nature of the mineralization, the assemblage of sulfide and alteration minerals, and the presence of open spaces with euhedral minerals, all point to an origin at shallow to moderate depths (a few hundred meters below surface) from hydrothermal solutions. The Yaxtché deposit shows alteration assemblages typical of high sulfidation epithermal deposits whereas the metal content and sulfide assemblages are characteristic of mineralizing fluids with an intermediate sulfidation state. The transition from high- to intermediate-sulfidation state is thought to define an evolving epithermal system as high-sulfidation state metal-bearing flu ........

Preliminary work was performed on four possible mining systems: post-pillar cut-andfill, transverse with pillars, transverse with cemented fill, and sublevel with end slicing.

The post-pillar cut-and-fill mining method was selected for the PEA evaluation.

This mining method relies on using 5 m x 5 m rooms and 5 m x 5 m square pillars. The pillars of one level are planned to align vertically with the next mining level to provide support. Mining starts at the lowest elevation in a mining area and is completed working upward. Some pillars can be extracted when they occur in an area of the stope where there will be no mining above.

Productivity calculations and unit costs for the final selection of a post-pillar cut-and-fill mine plan are based on the following criteria:

• Two 10 hr shifts per day, which yield 16 hr of actual work time.
• The ground is considered medium–hard for the drilling and blasting variable.
• Drilling of 18 ft (5.5 m) holes (providing 16.6 ft (5.1 m) of advance) with a two-boom production jumbo. Hydraulic drifter (drill) penetration rate is assumed to be 3.5 ft/min (1.1 m/min).
• No standard ground support is indicated; however, 1.5 hr per cycle is allotted for ground control (e.g. rock bolting), spot bolting or other cycle interruptions.
• Blasting will be carried out using gelatin-class dynamite and ammonium nitrate/fuel oil (ANFO) as the primary blasting agent. Non-electric (non-el) type ........

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