The Media Luna deposit is located on the south side of the Balsas River, ~7 km south south-west of the ELG Mine Complex.

The surface geology of the Media Luna area is dominated by Morelos Formation limestone which is intruded by numerous feldspar porphyry dikes and sills.

Systematic drilling has identified a gold-copper-silver mineralized skarn with approximate dimensions of 1.4 km x 1.2 km and ranging from 4 m to greater than 70 m in thickness. Skarn alteration and associated mineralization is open on the southeast, southwest, west and northwest margins of the area.

At Media Luna as well as in the deeper skarn zones of the Sub-Sill deposit, exoskarn is best developed in marble (Morelos Formation) at the contact with the main granodiorite and along the edges of feldspar porphyry dikes near that contact. Exoskarn typically consists of massive coarse- to fine-grained pyroxene and garnet. The contact between exoskarn and marble is typically sharp.

At Media Luna, there is a clear association of gold, copper and other metals with phlogopite, amphibole, chlorite, calcite ± quartz ± epidote alteration of skarn (amphibole–calcite alteration) and other mafic minerals and sulfidation of skarn, mafic minerals and magnetite. This mineral assemblage can occur as pervasive replacement of skarn minerals sometimes preserving garnet grain outlines or as veinlets with black chlorite or amphibole halos cutting across massive skarn bands.

Gold–copper–silver mineralization at Media Luna is associated with skarn alteration (pyroxene–garnet– magnetite) and later sulfides, which developed at the contact of granodiorite with marble. There is a clear association of gold, copper and silver with retrograde amphibole, phlogopite, chlorite, calcite ± quartz ± epidote alteration of exoskarn. This mineral assemblage can occur as pervasive replacement of skarn minerals, sometimes preserving garnet and pyroxene outlines, or as veinlets with black chlorite or amphibole halos cutting across massive skarn bands. Sulfidation of skarn assemblages is closely related to retrograde alteration and is extensively developed at Media Luna. Mineralization is primarily associated with sulfidized exoskarn and with zones of massive magnetite–sulfide. Mineralization does occur within endoskarn but is much less significant.

The ML mineral resource is a shallow dipping skarn deposit with a dip of approximately 35° to the south west and mineralization thickness varying between 5 m and 70 m. The mineralized skarn is located between a marble hanging wall and granodiorite footwall.

A review of the ML mineral resource identified three distinct and separate areas of higher tonnage and grade. Based on this assessment, a conceptual mining plan was developed which establishes three independent but connected mining zones; MLL, MLU and EPO zones. This plan provides operational flexibility for planning and scheduling while targeting high grade material early in production life. The conceptual mine design considers the three zones as independent mining areas that share a main access and materials handling system to transport mineralized material across the Balsas River to the ELG process plant. Processing of the ML mineralized material would take place in the existing ELG process plant, with an additional flotation and thickening circuit added to the plant for copper concentrate production.

Access to the Media Luna mineral resource would originate from the ELG Mine Complex and remain in service for the life of the operation. An elevated cable crane system (Ropeway) would be established to cross the Rio Balsas river and access the tunnel collar locations at ML. The Ropeway would provide transportation of equipment, materials and personnel to the twin tunnels during initial development and production. Alternatively, personnel that reside close to the river would travel to ML by boat, followed by road transportation to the portal.

A Suspended Conveyor would be installed from the ELG Mine Complex to the 655 elevation at MLL. The conveyor would travel via a tunnel through the El Limón ridge, continue across the Rio Balsas river, entering the Media Luna ridge and terminate at the MLL mining area. The conveyor would transport mineralized material and waste to the ELG stockpile locations and tailings back for use as backfill.

Media Luna is a shallow dipping skarn deposit with mineralization thickness varying between 5 and 70 meters.

Based on a review of the geology and shape of the Media Luna resource including a preliminary geotechnical review, LHOS was selected as the main mining method. In areas where the mineral resource is narrow, C&F stoping is utilized.

Preliminary mining stope shapes were estimated using Datamine’s Minable Shape Optimizer (MSO). The range of stope dimensions evaluated were first constrained by geotechnical parameters and maximum allowable hydraulic radii, followed by an economic evaluation. This work resulted in the selection of LHOS nominal stope size of 25 m high by 20 m wide by 30 m long. Development was planned to provide access using sublevels at 25 m spacing (elevation). C&F stopes were designed in areas where LHOS could not be used. Based on the conceptual mine plan, LHOS would contribute approximately 66% of the total production with the remaining 34% being C&F.

LHOS with Delayed Backfill
LHOS would be the primary mining method employed. This method was selected based on its lower operating cost, high productive capacity, and flexibility relative to other mining methods. Mining would progress from the bottom-up using a primary-secondary mining sequence. This design and sequencing allows for a number of stopes to be in production simultaneously which supports the planned production rate of 7,800 tpd and increasing to 8,500 tpd later in the mine life.

Longhole stopes would be accessed from undercut and overcut crosscuts. Mucking of blasted material would occur from the undercut, while fan drilling would take place from the overcut. Backfill using waste rock or paste would be placed in the open stope from the overcut. A sublevel interval of 25 meters has been selected and measured from floor of undercut to floor of overcut.

Cut and Fill (C&F)
In narrow sections of the deposit (less than 7 meters wide), the overhand C&F method would be utilized without pillars. In areas with mineralization greater than 7 meters in width, the Post Pillar Cut and Fill (PPC&F) mining method would be utilized to allow for multiple longitudinal cuts prior to backfilling. Pillar dimensions are estimated at 4 meters by 4 meters with a span between pillars of 7 meters.

Process unit operations that will be used include:

- Primary crushing*
- SAG mill grinding*
- Ball mill grinding*
- Copper Sulphide rougher flotation
- Cu-Au-Ag 1st, 2nd and 3rd cleaner flotation
- Fe-S rougher flotation
- Independent cyanidation leach and CIP circuit for Fe-S concentrate
- Independent DETOX for Fe-S Concentrate leach residue
- Separate water systems for fresh and cyanide containing water for flotation and leach circuits respectively
- Dewatering of flotation tailing
- Separate filtration of Cu-Au-Ag and Fe-S concentrates
- Leaching* and CIP* of flotation tailing
- Carbon stripping* and doré production* of carbon harvested from both CIP circuits
- Precipitation of copper in leach liquor via the SART* process
- Transfer of Fe-S Concentrate after filtration of leach residue to ML UG for use as paste
- Filtration* of leached flotation tailing and stacking of filtered tailing*
- Individual process water loops for grinding- flotation and leaching circuits
* denotes use of existing ELG processing plant equipment