According to Pearson and Speirs (2009), the El Limon vein system is classified as a low sulphidation epithermal system.

Gold mineralization in the Limón district is structurally controlled and forms veins that occupy pre-existing fault structures and extensional openings formed during mineralization. The veins are quartz dominant with lesser and variable quantities of calcite, and minor adularia. Pyrite is the predominant sulphide, but with a content of less than one percent. Trace amounts of chalcopyrite, sphalerite, arsenopyrite, altaite, gold tellurides, and native gold are also reported to occur. Gold is present in both the banded quartz and silicified breccias that form the veins. Gold is very fine-grained within the quartz vein, and is relatively uniformly distributed throughout the higher-grade parts of the veins; only once has visible gold been reported on the El Limón Mine concession.

The productive vein systems are approximately one to two kilometres long, with vein widths from less than one metre up to 25 m. Individual mineralized shoots within the veins range from 60 m to 450 m long horizontally, and from 40 m to 290 m vertically. Strike orientations vary from north-northwest through northeast to east-west, and dips are from 40° to nearly vertical. All economic gold mineralization discovered and mined to date lies within 400 m of surface. The productive and prospective elevations within the vein systems vary across the district. Post-mineral faults locally disrupt and offset the vein.

The gold-bearing veins and attendant alteration are hosted within volcanic flows, volcaniclastic strata, and possibly hypabyssal intrusions of the lowest volcanic unit. The other three gently dipping volcanic units are variously altered by the same hydrothermal fluids that deposited the gold veins, locally quartz stringers with low gold values are found in the massive porphyritic andesite flows that immediately underlie the unconformity contact with the youngest flat-lying unit. The youngest volcanic unit appears to post-date gold mineralization because no veins or vein-related alteration has, as yet, been identified within this unit.

The most extensive areas of argillic and quartz alteration form a corridor that crosses the El Limón mineral concession along a roughly west to east trend, this alteration corridor is mostly located to the south of the Talavera, Limón, and Santa Pancha-Panteón vein systems and is partially capped by the young, flat-lying volcaniclastic unit. Much of this alteration is part of the upper, near-paleosurface component of the low-sulphidation epithermal system that formed the productive gold veins. Preliminary mapping indicates the presence of both distal and proximal alteration facies related to the epithermal system.

The identification of the proximal alteration facies, combined with the presence of auriferous quartz vein boulders and silicified, steeply inclined structures, provide exploration guides for the discovery of new gold-bearing vein systems, and increase the exploration potential along this corridor.

El Limón mining units include the Santa Pancha 1, Santa Pancha 2, and Veta Nueva underground mines and the Limón Central open pit mine.

Mining operations use conventional open pit mining methods at the Limón Central open pit and a combination of top-down and bottom-up sequenced longitudinal open stoping (LOS) at El Limón underground mines.

All underground mines are ramp accessed using a variation of the LOS method for ore production. The Santa Pancha mine currently experiences groundwater at 70°C and inflow rates of up to 95 litres per second, while the SP2 and Veta Nueva mines do not experience significant groundwater inflows. An underground mine dewatering system has been installed at SP1 to manage groundwater inflows. The SP1 mine operates at elevated temperatures as a result of the hot groundwater and virgin rock temperatures, and mine ventilation is used to cool the mine and remove contaminants. Fresh air enters the mine at the portal, is drawn down the ramp, onto the main levels, and exhausts from the mine via ventilation raises.

The Limón Central pit will be a conventional open pit mine with 6 m bench height, using drill and blast for rock breakage and excavators and trucks for materials handling. The vein and stockwork zones will be mined selectively. The pit ramps were designed at 10% maximum gradient and 17 m width for double lane traffic, with the exception of the last four benches of the ramp in the pit bottom, where the ramp is narrowed to a width of 11 m, and suitable for single lane traffic. The ultimate pit bottom is planned at the -18 m elevation. The highest pit wall of 200 m will be achieved in Phase 3. The design premise was to mine the pits to a minimum mining width of 30 m with the pit bottom as a narrow bench excavated with a backhoe to reduce the mining width 20 m.

Production from underground and surface mines is combined to feed the El Limón processing plant with a nominal capacity of 500,000 tpa. For the remaining LOM, underground mines combine to produce 500 tpd, Limón Central production rates range from 850 tpd to 1,150 tpd, and the El Limón process plant is fed at a rate of approximately 1,450 tpd.

Underground Mine Design
The Santa Pancha deposits extend to 300 m below surface. The orebodies are generally steeply dipping with the dip varying between 65° and 70°. Underground mining at the Santa Pancha mines will be carried out using a combination of top-down sequenced LOS with sill pillars and bottom-up sub-level stoping (SLS) with backfill.

The Veta Nueva deposit is a steeply dipping orebody extending 150 m below surface. The orebody thickness ranges from 3 m to 10 m. The deposit has been designed and scheduled to use SLS in a bottom-up fashion.

LOS will be accessed from the FW with ore drives developed along the veins. The stopes will be drilled and mucked from the undercut retreating towards the access drift. SLS stopes will be accessed by an undercut drift and a topcut drift. Production drilling is accomplished from the top cut and mucking from the undercut. Each level will be mined using a retreat approach where on vein development progresses centre out and stope production starts at the end and retreats towards the access point. Stopes on a given level will be completely mined and filled with unconsolidated fill prior to mining progressing to the next level. Waste rock for backfill will be sourced from underground development waste and surface waste stockpiles.

Open Pit Mining
The El Limón open pit deposits are subdivided into five zones; Tigra/Chaparral, Limón North, Limón Central, Limón South, and Pozo Bono. The Limón Central deposit contains Mineral Resources classified as Indicated and Inferred, while the Mineral Resources at the remaining deposits are classified as Inferred. The Limón Central Mineral Reserves in this report are based on Indicated Mineral Resources only, above a cut-off grade of 1.32 g/t Au, contained between the end of June 2019 surface and the ultimate pit design.

The ore zone consisting of vein/quartz breccia and stockwork zones is mined selectively.

A scoping level mine design and production schedule was developed for the Limón Central deposit based on an open pit mining method. Mining will be undertaken by contractor using conventional truck and loader equipment. Mining through the backfilled underground workings is a manageable risk, however, it may result in unplanned delays and additional costs.

The mine plan for the open pit mine results in production of approximately 300,000 tpa mill feed. The Limón Central pit has been operational since December 2018, and a substantial portion of the overlying barren rock has been removed in a "pre-stripping" phase to expose the initial ore for production.

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The Limón processing plant is a conventional processing plant consisting of agitated cyanide leaching and carbon adsorption, followed by carbon elution, electrowinning, and doré production.

The processing plant consists of the following unit operations:

- Single-stage crushing with a jaw crusher capable of processing approximately 100 tonnes per hour (tph) and a crushed ore stockpile.

- Two-stage grinding to 90% passing 75 µm utilizing a conventional semi-autogenous grinding (SAG)-ball mill circuit (without a pebble crusher); the SAG and ball mills are 17.5 ft x 6.7 ft and 745 kW and 12 ft x 16 ft and 1,050 kW, respectively. Pebbles are periodically returned to the grinding circuit.

- Pre-leach thickening to 43% solids, followed by leaching in five leach tanks (2 x 1,100 m3 and 3 x 955 m3) with oxygen addition, and carbon adsorption in eight 40 m3 carbon-in-pulp (CIP) tanks.

- Tailings disposal by pumping to the lined San Jose TSF. ........