The skarn zone at the El Limón deposit occurs at the stratigraphic level of the Cuautla Formation where marble is in contact with hornfelsed sedimentary rocks of the Mezcala Formation. Significant gold mineralization at El Limón is generally associated with the skarn, preferentially occurring in pyroxene-rich exoskarn but also hosted in garnet-rich endoskarn.

The El Limón Sur zone occurs approximately 1 km south of the main El Limón skarn deposit and appears to be an oxidized remnant of skarn emplaced at the contact between the intrusive and the host rocks represented by the marble and hornfels.

The Guajes skarn zone is developed in the same lithologies on the opposite side of the same intrusive present at El Limón. Marble (Morelos Formation) forms the footwall and a hornfels (Mezcala Formation) forms the hanging wall.

At the Guajes deposits the intrusion underlies the sedimentary rocks and the contact dips at about 30° to the west, sub-parallel to bedding.
At ELG Mine, gold occurs most often with early sulphide mineralization but also with late carbonate, quartz, and adularia. Native gold most commonly occurs in close association with bismuth and bismuth tellurides but also occurs with chalcopyrite and as inclusions in arsenopyrite. The dominant sulphides are pyrrhotite and pyrite with lesser but locally abundant amounts of chalcopyrite and arsenopyrite occurring in veinlets and open-space fillings.

The ELG Mine is being developed with standard open pit mining methods. Key characteristics of these deposits from an open pit mining perspective include very steep and irregular terrain, proximity to the village of La Fundición located downhill from the El Limón deposit, relatively competent bedrock, and poorly defined ore-waste contacts.

Dozing requirements will be performed by a fleet of two 455 kW tracked bulldozers and three 335 kW tracked bulldozers. These units were acquired in 2013 and 2014, since they were needed in the Guajes dozer pits at the start of pre-production development. After dozer pit mining is complete the units will be utilized in the truck-loader pits and on the waste dumps. Two 393 kW rubber-tired dozer units are included in the mine plan, to work principally on bench cleanup around the shovels, and on road maintenance.

The design basis for the processing facility is 14,000 tonnes per day or 5,040,000 tonnes per year at 90% mill availability. This section presents the process design criteria that will govern the design of the processing facility (mill) including crushing, grinding, agitation leaching, carbon adsorption, carbon desorption (stripping), carbon regeneration, gold electrowinning, gold refining, tailing detoxification, tailing filtration and disposal. The process plant designed for the ELG Mine utilizes processes and equipment which are standard for the industry. This includes cyanide leach followed by carbon-in-pulp recovery, and utilizing filtered tailing for disposal.

-Size reduction of the ore by a gyratory crusher, wet semi-autogenous grinding mill (SAG), and ball milling to liberate gold and silver minerals.

-Thickening of ground slurry to recycle water to the grinding circuit.

-Recovery of precious metals contained in the recycle water by carbon columns (CIC).

-Cyanide leaching of the slurry in agitated leach tanks.

-Adsorption of precious metals onto activated carbon by carbon-in-pulp (CIP) technology.

-Removal of the loaded carbon from the CIP and CIC circuits and further treatment by acid washing, stripping with hot caustic-cyanide solution, and thermal reactivation of stripped carbon.

-Recovery of precious metal by electrowinning.

-Mixing electrowon sludge with fluxes and melting the mixture to produce a gold-silver doré bar which is the final product of the ore processing facility.

-Thickening of CIP tailings to recycle water to the process.

-Detoxification of residual cyanide in the tails stream using the SO2/Air process.

-Filtering of detoxified tailings to recover water to recycle to the process.

-Disposal of the filtered detoxified tailings to a dry stack tailings pad.

-The water from filtrate solution pond is recycled for reuse in the process. Water stream types include: process water, fresh water and potable water.

-Storage, preparation, and distribution of reagents to be used in the process. Reagents which require storage and distribution include: sodium cyanide, caustic soda, flocculant, copper sulphate, sodium metabisulphite, hydrochloric acid, and lime.