Mineralization consists of polymetallic, high-temperature, intrusion-related carbonate-replacement and minor skarn-hosted deposits. Mineralization occurs as tabular veins, mantos, massive lenses, breccia pipes, and irregular replacement zones.

The deposits were grouped into four geological zones: the Prieta complex, the San Javier–Milagros complex, the Vein systems, and Tailings Deposit No. 4.

Discordant, near-vertical deposits with irregular elongate shapes proximal to main intrusions are referred to as chimneys and breccia pipes. These include the San Javier, Milagros and Prieta breccia deposits.

Tabular sub-vertical replacement deposits are referred to as veins and can contain richer mineral shoots or small chimneys at the intersection of northwest-trending faults and fractures. Steeply dipping, tabular deposits of the Vein systems have a northeast orientation, and are commonly distal to main intrusions.

Massive lens replacement zones of the Prieta complex are proximal to a granodiorite source intrusion and formed adjacent to skarn alteration. Contact metamorphic features (recrystallization to marble, development of hornfels and skarnoid) normally occur peripheral to the skarn zone.

Mineralization consists of secondary oxide minerals including silver, iron, zinc, lead, copper oxides and native silver. Native silver and oxide minerals also occur with sulphides in skarn and carbonate replacementzones where sulphides ar ........

La Encantada Silver Mine included two main underground silver mines: the La Encantada and the El Plomo mines. Mining activities are conducted by both First Majestic and contractor personnel.

The deposits vary in dip, thickness, and geotechnical conditions along strike and dip. Multiple mining methods are required to achieve the maximum efficient extraction of mineralization. Three well established methods were selected:
• Inclined and sublevel caving;
• Long hole stoping;
• Cut-and-fill.

Inclined and sub-level caving is well suited for the bulk tonnage deposits at La Encantada such as the San Javier–Milagros breccia and the Ojuelas deposit. Longhole stoping is being used for near vertical structures that are relatively consistent along strike and length and have competent wall rock. The minimum planned mining width is 1.4 m, based on a minimum vein width of 1.0 m plus an allowance for 0.2 m on the hangingwall and footwall. The stopes are drilled using a basic two-hole pattern when the width is <1.5 m, increasing the number of drill holes per section as the vein increases in width. Cut-and-fill is performed using jackleg drilling and is used for vein deposits that are irregular in nature and commonly possess poorer geotechnical conditions. The minimum mining width is 1.3 m, based on a minimum vein width of 1.0 m and an additional 0.15 m was added to both the hangingwall and footwall as planned dilution using the stope optimizer.

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