The Ermitaño project gold and silver deposits form as prominent east–west-trending veins and associated breccias in sub-aerial felsic volcanic rocks. The Ermitaño Vein is delineated by drilling along an 1,850 m strike length and vertically over 550 m, starting at surface.

The regional geology and the form, textures, alteration, and mineralization observed to date within the Ermitaño deposit are diagnostic of low-sulphidation epithermal mineralization. The Ermitaño Vein is hosted in a sequence of volcanic lavas and tuffs and displays epithermal minerals and textures.

Exploration programs that use a low-sulphidation epithermal model are considered appropriate for the Santa Elena and Ermitaño areas. First Majestic is using geochemical and geophysical surveys, and field X-ray fluorescence analyzers and spectrometers as part of its ongoing regional exploration program. Mapping, rock chip sampling and drilling of vein outcrops remain the primary exploration tools at Santa Elena and the Ermitaño project.

Mineralizing fluids are interpreted to have used the Ermitaño Fault as a conduit to form the Ermitaño Vein and sub-parallel tertiary veins which drilling has delineated over 1,800 m along strike and 550 m down dip. The vein is best developed where the structure cuts the older brittle volcanic rocks, where the older volcanic rocks are juxtaposed with younger brittle volcanic rocks, and where the structure shows deflection.

A four-stage vein ........

The Santa Elena mine operation consists of the Santa Elena underground mine and the Ermitaño project. Mining activities are conducted by both First Majestic and contractor personnel. The Santa Elena and the Ermitaño deposits vary in dip, thickness, and geotechnical conditions along strike and dip. Multiple mining methods are required to achieve the maximum efficient extraction of mineralized material at site. Three well-established methods were selected for mining extraction at Santa Elena:
• Longitudinal longhole stoping;
• Avoca;
• Cut-and-fill.

The Avoca mining method was selected for the Ermitaño project.

Site geology at the Ermitaño project consists of Late Cretaceous andesite and rhyolite volcanic rocks dipping 10° to 45° east-northeast with mineralization hosted by major structures. The geology and mineralization are similar to the Santa Elena deposit located 8 km to the northwest. Low sulphidation epithermal gold and silver mineralization is hosted in the steeply dipping, east trending Ermitaño Fault and other subparallel secondary structures. Vein assemblages consist of massive, banded, bladed, and stockwork quartz, calcite, and adularia. The veins are commonly brecciated and associated with argillic alteration.

Based on the configuration of the deposit, longhole open stoping was selected as the mining method. Three variations of longhole open stoping were considered, driven by economics: Avoca longhole stoping wit ........

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With the introduction of mineralized material from Ermitaño, the plant will continue to process the Santa Elena blend in campaigns alternating with fresh material from Ermitaño. For the achievement of optimum levels of metal recoveries and the corresponding maximum metal production, the Santa Elena ore will be processed at higher throughput rates than the Ermitaño ore during their corresponding production campaigns. Average operating throughput targets are 3,350 and 2,350 tpd for Santa Elena and Ermitaño, respectively. The rationale behind the throughput difference is due to the higher hardness, abrasiveness, and particle size sensitivity of the Ermitaño ore when compared to Santa Elena ore. Both campaigns are expected to achieve a final particle size 50 microns P80 at their respective optimum operating conditions until the commissioning of the additional tailings filtration circuit, which is based on pressure filtration. After the commissioning is completed in Q3-2022 the grind size ........