Mineralized veins at El Cubo consist of the classic banded and brecciated epithermal variety. Silver occurs primarily in dark sulfide-rich bands within the veins, with little mineralization within the wall rocks. The major metallic minerals reported include pyrite, argentite, electrum and ruby silver, as well as some galena and sphalerite, generally deeper in the veins. Mineralization is generally associated with phyllic (sericite) and silicification alteration which forms haloes around the mineralizing structures. The vein textures are attributed to the brittle fracturing-healing cycle of the fault-hosted veins during and/or after faulting.

Most production is extracted from two of the principal district vein systems, the Veta Madre (Las Torres lease only) and La Sierra (El Cubo mine). Economic concentrations of precious metals are present in “shoots” distributed vertically and laterally between nonmineralized segments of the veins. Vein intersections are locally the site of important historic bonanzas, notably the San Nicolas-Villalpando intersection, nearly perpendicular, and the intersections of various named splays along the principal El Cubo vein, the Villalpando vein. Overall, the style of mineralization is pinch-and-swell with some flexures resulting in closures and others generating wide sigmoidal breccia zones.

Primary economic mineralization at El Cubo is gold and silver. Base metal values are generally absent, except for small amounts of chalcopyrite. El Cubo appears to be a low sulfidation system with pyrite but no arsenopyrite.

The silver-rich veins, such as Villalpando, contain quartz, adularia, pyrite, acanthite, naumannite and native gold. Native silver is widespread in small amounts. Much of the native silver is supergene. Silver sulfosalts (pyrargyrite and polybasite) are commonly found at depth. Gold rich veins, such as San Nicolas, contain quartz, pyrite, minor chalcopyrite and sphalerite, electrum, and aguilarite.

A vertical mineralogical zonation occurs in the vein system. The upper-levels are acanthite + adularia + pyrite + electrum + calcite + quartz and the lower-levels are chalcopyrite + galena + sphalerite + adularia + quartz + acanthite.

The gold/silver ratio in the more gold-rich veins typically ranges from 1:15 to 1:30. The gold/silver ratio in the silver rich veins typically ranges from 1:60 to 1:150, and sometimes higher. The overall gold/silver ratio for the 37 veins included in the resources and reserves is 1:64. Ranges for gold/silver ratios at El Cubo vary from 1:10 to 1:20 in upper mine levels, from 1:40 to 1:50 in middle mine levels; and 1:100 to 1:150 at depth. Veins are barren below an elevation of about 1800 m.

Conventional drill and blast methods are used to extract the ore at El Cubo, and access to the mining areas is provided by ramps, adits and shafts. Mine development headings are drilled by jumbo and by jackleg. The dimensions of the different development sections are as follows:
- Main Ramps: 4.3 W x 4 H meters
- Accesses: 3 x 3 meters
- Sill in Mineral 2.2 x 2.5 meters (minimum)
- Raise: 1.5 x 1.5 meters
- Bore Holes Raise: 1.8 meter diameter.

The choice of equipment is generally guided by the anticipated vein widths, stoping method, and equipment availability.

The stoping methods used at El Cubo in 2016 were mechanized cut-and-fill and long hole. These two methods are also planned for all the future production.

Once sill development is completed and the limits of the ore have been defined, stope production can begin. For conventional cut and fill stoping, ore is mined upward in horizontal slices using jackleg drills. Cut and fill mining is a method of short hole mining with hole lengths usually less than 2m. After the ore is removed, the void is filled with muck. El Cubo uses unconsolidated mine waste from development headings. Under certain circumstances concrete is used as fill to create a solid floor. This enables mining from the stope below up to the concrete pillar and recovering most, if not all of the ore pillar that would otherwise be left behind. This process is usually reserved for high-grade floor pillars.

The mining is simpler where the veins are close to, or equal to the width of the working. In this case, the back is blasted full-width and the extra waste blast step is eliminated.

By comparison, longhole open-stoping, holes are drilled upwards and/or downwards from the sill level. Longhole methods are typically 7 to 15m in length and are more productive than cut and fill methods. Longhole stoping is also cheaper than conventional cut and fill stoping. As with cut and fill methods, longhole stopes are filled with waste rock from development headings.

Some of the ore produced with the longhole drill machines is generated by drilling old pillars. Other stopes are blind by drilling uppers and blasting a slot at the far end of the stope to enable the ore to break in the subsequent larger stope blasts. Uppers are drilled to a 10-15m height on vein projections in rows across the width of the vein. The rows closest to the slot are blasted first. The stope is mucked clean, or at least sufficiently to allow the next blast. The stope retreats, leaving a void that can only be filled by a mill hole connected from somewhere above. The ore is extracted using remote- controlled scoops.

In December 2013 the leaching plant was shut down due to the fact that selling the concentrate was more economic than cyanide leaching at current conditions.

The recovery process at El Cubo during 2016 consisted of a single flotation concentrate.