Gold-silver mineralization on the Mercedes property is hosted within epithermal low sulphidation (adularia-sericite) veins, stockwork, and breccia zones.

A total of 16 principal low sulphidation epithermal vein/stockwork/breccia zones, have been identified on the Mercedes property. The currently producing veins have been divided into three sub-district areas:
• Mercedes Area (Mercedes-Barrancas)
• Klondike Area (Klondike-Rey de Oro)
• La Lupita Area (Lupita-Diluvio).

The majority of the veins are hosted within the andesite package, or locally at the fault contact between andesite and the underlying lithic tuff package. Only the Diluvio zone at Lupita and the Anita veins contain significant economic grade mineralization hosted completely in the lower tuff package.

The mineralized zones display a combination of fissure vein, stockwork, and breccia morphologies that change rapidly on strike and dip. The zones range in width from less than one metre to composite vein/stockwork/breccia zones up to 15 m wide. In the Diluvio zone, gold-silver bearing vein/stockwork zones locally attain thicknesses in excess of 100 m. Length of individual veins varies from 100 m to over two kilometres. Property-wide, Au-Ag bearing veins occur over a vertical range greater than 600 m (680 m to 1,300 m).

The Mercedes vein is the most important and continuous vein system identified on the property to date, with quartz-carbonate veining being traced almost continuously on strike for nearly 3.5 km. The Mercedes fault system consists of numerous anastomosing strands within a zone over 50 m wide. Emplaced within these faults in extensional open areas were a series of complex, multi-stage, anastomosing vein/breccia/stockwork zones one metre to 15 m wide. Vein mineralogy (multiple quartz and carbonate stages) and morphology change rapidly along strike and down dip. Mineralized green-grey sugary to chalcedonic quartz is often highly brecciated and cemented by 15% to 80% late stage grey calcite, rhodochrosite, and/or brownblack manganese-iron carbonates.

The Klondike vein zone trends N70ºW, dipping 65º to 80º southwest. It is approximately 800 m long, with a maximum vertical range of nearly 300 m and width ranging from 0.5 m to over 50 m.

The Klondike vein system is significantly different from that at Mercedes, in that it typically forms as a tectonic breccia zone rather than fissure fill vein. Within the breccia zone, there are highly variable lenses of brecciated white to green or grey quartz and abundant manganese carbonates and calcite. Fissure filling veins over 0.5 m wide are rare, while the overall zone of crackle brecciation and stockwork veining with silicification and strong manganese-iron oxides may be up to 50 m in width.

The Lupita vein zone outcrops on surface for 1,800 m following a contact between the overlying andesite package and underlying quartz-crystal lithic tuff package. In outcrop, the vein zone ranges from one metre to five metres thick. Multi- stage quartz-carbonate ± adularia veining locally extends continuously down dip in places more than 450 m along most of the west half of the surface outcrop.

Most importantly, at depths of 200 m to 300 m in the Diluvio zone, an extensive zone of multistage quartz-carbonate ± adularia vein breccias, stockwork, and hydrothermal breccia up to 150 m thick has been identified that is primarily hosted in the lower lithic tuff-volcaniclastic sequence. Based on preliminary geologic interpretation, it is proposed that the tuff/volcaniclastic sequence hosting the main portion of the Diluvio deposit is a large fault block that was displaced down the Lupita fault structure prior to andesite deposition. Diluvio therefore is the only mineral deposit in the district with the lower lithic tuff/volcaniclastic sequence as the primary host.

The Mercedes operation consists of five separate underground mines, all of which are in the production planning stage; plus an open pit mine that is in the planning stage. The five underground mine areas are:
1. the Mercedes Mine area composed of Corona de Oro (CDO), Casa Blanca, Brecha Hill, and Brecha Hill Norte;
2. the Barrancas-Lagunas mine area composed of the Lagunas, Barrancas Centro, and Barrancas Norte;
3. the Lupita mine area;
4. the Diluvio mine area;
5. the Rey de Oro mine area composed of both an underground operation and a very small open pit, which is under evaluation, and requires permitting. The permitting of this open pit is expected to be completed in mid-2018 according to MMM staff.

Production will come from the Mercedes, Barrancas- Lagunas, Lupita, Diluvio, and Rey de Oro. Access to all of the mines is by way of declines. The Rey de Oro area is contiguous with and immediately south of the mined-out Klondike deposit and will incorporate many of the methods and infrastructure from this older mine area.

The underground mines are all designed as ramp access mechanized mines. The anticipated ore production rate ranges from 1,700 tpd to 1,900 tpd (average 1,800 tpd) which is lower than the designed 2,200 tpd capacity. Ore from underground is hauled by 16 t trucks to stockpiles near the portals. Ore from the Barrancas-Lagunas, Lupita, Diluvio, and Rey de Oro mines is hauled to a common stockpile area near the jaw crusher.

The mine schedule is based on a seven days in/seven day out roster for 365 days per year. Crews work 12-hour shifts; planning is based upon the loss of three hours per shift for breaks, safety meetings, equipment checks, and minor maintenance. The total hours worked per year per person on this schedule is 2,190 hours. The available working time per shift equates to an average availability of 75% of the total hours.

Until 2018, there were two underground mining methods in use at Mercedes. Approximately 90% of the rock was mined by mechanized CAF stoping. Where the rock quality was appropriate, the ore was mined by long hole open stopes (LHOS) with cemented paste backfill. However, for the 2018 LOM production plan reviewed under the scope of this report, MMM staff reported that the mining method is wholly mechanized CAF stoping with no LHOS mining.

The CAF method is further subdivided into two types of mining, Full Face and Split Blasting. In areas where the full face (3.5 m width) does not meet the cut-off grade criteria, split blasting is considered. With split blasting, the round is taken with two blasts. First the mineralized zone is blasted and mucked, followed by a waste cut being blasted and mucked in order to meet the minimum mining width of 3.5 m. This allows narrow zones to be mined with reduced dilution. The mineralized cut for split blasting has a minimum width of two metres and any non-vein material included in the cut is assumed at zero grade. Split blasting is only assumed in select areas where there is a history of successfully implementing this technique.

The open pit mine at Rey de Oro is a small open pit, which extends up a slope. The pit contains approximately 114,000 tonnes of ore, which is a 25% decrease from the 2016 Mineral Reserve of 151,000 tonnes. Due to the low tonnage, the most reasonable mining scenario appears to be contract mining with technical supervision and grade control provided by Mercedes.

The processing facilities at Mercedes use conventional milling with Merrill-Crowe recovery of precious metals. The plant processes approximately 2,000 tpd. The plant consists of:
• Three stage crushing
• Single stage grinding and classification with cyclones
• Gravity concentration
• Agitated cyanide leaching
• Counter-current-decantation (CCD) thickener wash circuit
• Merrill-Crowe precious metal recovery circuit
• Cyanide detoxification of tailings
• Refinery.

Run of Mine (ROM) stockpiles ahead of the crusher are used to blend different grades of ore. ROM ore is transported to the crusher dump hopper. From the dump hopper the ore discharges onto a vibrating grizzly feeder that feeds the ore into the jaw crusher. The jaw crusher product discharges onto the crusher discharge belt feeder and onto a transfer conveyor that transports the crushed ore to the coarse ore bin.

A reclaim feeder transfers crushed ore from the coars ........