Deposit Types
Deposits at La Encantada are examples of polymetallic, high-temperature, intrusion-related carbonate-replacement and minor skarn-hosted deposits. The carbonate-replacement deposits are hosted by the Jurassic–Cretaceous Aurora Formation.

Mineralization
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) normall ........

The La Encantada mine operation consists of an underground mine. 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 breccias 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.

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.

Ground conditions throughout most of the La Encantada mine are considered good. In contrast, the breccia and massive lens-type deposits form weak, soft material that lends itself to caving mining methods. The ........

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