The Railroad-Pinion property includes demonstrated Carlin-type gold mineralization in at least four deposit areas: North Bullion, Pinion, Dark Star, and Jasperoid Wash. These deposits are similar in setting and style to that of other deposits in the region, including Rain and Emigrant (Koehler et al., 2014; Norby et al., 2015; Turner et al., 2015; Dufresne and Koehler, 2016). Mineralization occurs mainly as finely disseminated, submicroscopic gold in largely stratiform bodies in Devonian, Mississippian, and Pennsylvanian- Permian rocks. The following subsections describe the mineralization in the North Bullion, Pinion, Dark Star, and Jasperoid Wash deposits and are modified from Dufresne and Nicholls (2016; 2017a; 2017b; and 2018).

The Railroad-Pinion property has two adjacent parts, the North Railroad portion (“North Railroad”), which includes POD, Sweet Hollow, and North Bullion (collectively called the North Bullion deposits, or the North Bullion area), and the South Railroad portion (“South Railroad”), which includes Dark Star, Pinion, and Jasperoid Wash.

Pinion Deposit
The Pinion gold deposit is located along the west- northwest-trending Pinion anticline and proximal to the Bullion fault. The Main zone trends approximately N50°W to N60°W, is approximately 1,000 m long by 1,000 m wide, and varies in thickness between ~15 to 150 m vertically. Mineralization at the Main zone has been intersected to a depth of 200 m below surface. Mineralization is hosted primarily along the crest of the Pinion anticline, but also along the east and west limbs. The multi-lithic dissolution- collapse breccia at the Devils Gate-Tripon Pass contact hosts the majority of mineralization, with minor amounts associated with decalcified limestone and dolostone above and below the breccia.

The North zone is approximately 1,100 m long, along a roughly north-northwest trend, varies from 45 m to 100 m in width, and ranges from 35 m to 135 m in vertical thickness. Mineralization at the North zone is hosted primarily in multilithic breccia and appears to be an offset of the east limb of the anticline. Low-grade mineralization has also been noted in the Sentinel Mountain Dolomite.

Dark Star Deposit
The Dark Star deposit is hosted primarily within Pennsylvanian-Permian undifferentiated units possibly equivalent to the Tomera Formation, with minor amounts of gold mineralization found in the Chainman Formation. The deposit is centered along the north-south-striking Dark Star fault corridor and is elongate in the N5°E direction. As presently defined by drilling, the deposit consists of the Dark Star Main and Dark Star North zones, and has dimensions of approximately 1,400 m in length, up to 700 m in width, and to a depth of 450 m below surface.

Gold mineralization at Dark Star is submicroscopic and disseminated within a north- to north- northeast-striking zone of silicification within the middle coarse conglomeratic and bioclastic limestone-bearing unit. This unit is between the upper and lower silty limestone and calcisiltite units. At Dark Star Main the mineralization dips steeply to the west near the surface to sub- horizontal at depth; at Dark Star North the mineralization dips steeply to the west.

Jasperoid Wash Deposit
The Jasperoid Wash deposit has approximate extents of 1,400 m in a north direction and a width of about 1,100 m. Drilling shows the deposit dips west gently to steeply at least 400 m. Gold is disseminated within altered feldspar porphyry dikes and adjacent conglomeratic rocks, possibly the same units that host mineralization at Dark Star. The gold is inferred to be submicroscopic, though no petrographic studies have been done. Higher-gold grades are associated with drusy quartz in fractures, which have a varnish of limonite and/or hematite and with zones of very finegrained disseminated sulfide minerals that have a sooty appearance in the argillized feldspar porphyry.

The PFS includes mining at both the Dark Star and Pinion deposits; both are planned as open-pit, truck and shovel operations. The truck and shovel method provides reasonable costs and selectivity for these deposits.

The production schedule considers the processing of material by ROM, HPGR, and toll processing. HPGR stockpiles of lower-grade material will be utilized to ensure that higher-grade material is processed first. The stockpiles will be maintained near the crusher. All ROM material will be dumped in place directly on the ROM leach pad. Monthly periods were used to create the production schedule with pre-stripping starting in Dark Star at month -8. Start of ROM processing is assumed to be month 1. HPGR processing is started three years after the start of ROM processing. Prior to that time, the ROM material will be processed up to the maximum spray capacity of 22,500 tonnes per day of material or up to 8.2 million tonnes per year. Once HPGR processing starts, the maximum HPGR rate is targeted at 10,000 tonnes per day or 3,650,000 tonnes per year on a 365 day per year basis, and ROM processing is reduced as to not exceed the total spray processing available.

Toll processing occurs from Year 2 through Year 5, and the rate is limited to 500 tonnes per day. Only Dark Star sulfide material with greater than 1.17 g Au/t would be toll processed, and the material would be stockpiled near Dark Star prior to being loaded in a contractor’s over-the-road haul truck.

The total Dark Star mining rate would ramp up from 20,000 tonnes per day to about 60,000 tonnes per day over a period of 5 months. A maximum of 120,000 tonnes per day is used in the production schedule during the peak mining of deeper Dark Star material. Mining is to start in Dark Star North and Dark Star Main and then progress to Pinion in Year 4.

The PFS has assumed owner mining in order to keep the cost lower than it would be with contract mining. The production schedule was used along with additional efficiency factors, cycle times, and productivity rates to develop the first principle hours required for primary mining equipment to achieve the production schedule. Primary mining equipment includes drills, loaders, hydraulic shovels, and 136-tonne (150-ton) capacity haul trucks.

Waste storage facility designs were created for the PFS to contain the material that is not processed. A 1.3 swell factor was assumed which provides for both swell when mined and compaction when placed into the facility.

CRUSHING
High grade ore from the Pinion and Dark Star pits (approximately 34.2% of the total mineral reserves) will be crushed beginning in Year 4 of operations in a three-stage crushing circuit. Ore will be transported from the mine in surface haul trucks and dumped either directly into the crusher dump hopper, or at the crusher area stockpile where it will be reclaimed and fed to the crusher hopper by a loader. The dump hopper will be equipped with a static grizzly with 762 mm openings to prevent oversize rocks from being fed to the crushing circuit. Blending will be required for some ore types, especially for higher clay areas. The crushing plant will process an average of 10,000 tonnes of ore per day.

Ore will be fed from the ROM dump hopper to a vibrating grizzly feeder via an apron feeder. The vibrating grizzly feeder will have parallel bars spaced 100 mm apart with grizzly oversize being fed to the primary jaw crusher and the grizzly undersize being recombined with the jaw crusher product on the primary crusher discharge conveyor. The primary jaw crusher will operate with a 102 mm discharge setting. The primary crusher discharge conveyor transfers primary crushed ore to the primary crushed ore stockpile feed conveyor. The primary crushed ore stockpile has a total capacity of 16,000 tonnes with a live capacity of 4,100 tonnes (approximately 9 hours of operation).

Ore from the primary crushed ore stockpile will be reclaimed by two each vibrating pan feeders onto a secondary screen feed conveyor. A tramp metal electromagnet and metal detector will be installed on the secondary screen feed conveyor to protect the secondary crushers. The secondary screening circuit includes a single double-deck vibrating screen with 76 mm and 50 mm top and bottom deck openings, respectively. Oversize material (+50 mm) will be transferred to the secondary feed conveyor by the screen oversize conveyor and undersize (-50 mm) will be transferred to the secondary product stockpile feed conveyor by the secondary screen undersize conveyor. Oversize material will be crushed by a secondary standard cone crusher which will operate with a 50 mm closed side setting and will discharge onto the secondary crusher product conveyor. The secondary crushing circuit will be operated in closed circuit with the secondary crusher product conveyor feeding the secondary screen feed conveyor; a splitter chute with a flop gate is positioned at the discharge of the secondary crusher product conveyor to bypass secondary cone product from the secondary screen and tertiary crusher circuit by feeding material directly to the tertiary crusher product stacking conveyor. Due to the high abrasiveness of the ore, a second standby cone crusher is included in the design to meet plant availability requirements.

The secondary screen undersize (secondary product) will be stockpiled by the secondary stockpile feed conveyor. The secondary product stockpile will have a total capacity of 16,000 tonnes with a live capacity of 4,100 tonnes. Ore from the secondary product stockpile will be reclaimed by two vibrating pan feeders each onto the HPGR feed conveyor. A tramp metal electromagnet and metal detector will be installed on the HPGR feed conveyor to protect the HPGR (high pressure grinding roll) crusher.

The tertiary crushing circuit will consist of an HPGR crusher with partial recycle. Ore will be fed to the HPGR feed bin which choke feeds the HPGR unit. Approximately 20% of the HPGR product is recycled back to the HPGR feed conveyor. Crushed product from the HPGR, 100% passing 14 mm, is stockpiled by the tertiary crusher product stacking conveyor.

Modular motor control centers will be located in containers near the primary, secondary, and tertiary crushing circuits. A PLC control unit will be located in a central control room which will control and monitor all crushing equipment, as well as monitor the conveyor stacking equipment. All of the conveyors will be interlocked so that if one conveyor trips out, all upstream conveyors and the vibrating grizzly feeder will also trip. This interlocking is designed to prevent large spills and equipment damage. Both of these features are considered necessary to meet the design utilization for the system.

Water sprays will be located at all material transfer points to reduce dust generation by the crushing circuit.

The process selected for recovery of gold and silver from the Pinion and Dark Star ore is a conventional heap-leach recovery circuit. The ore will be mined by standard open pit mining methods from two separate pits. Lower-grade Pinion and Dark Star ore will be truck-stacked on the heap as ROM ore directly, without crushing. Higher grade Pinion and Dark Star (low clay) material will be processed in a three-stage crushing circuit with a high-pressure grinding roll (HPGR), treated with cement and agglomerated, then conveyor-stacked onto heap leach pads.

Oxide and transition material types will be leached with a dilute cyanide solution, and the leached gold and silver will be recovered from solution using a carbon adsorption circuit. The gold and silver will be stripped from carbon using a desorption process, followed by electrowinning to produce a precipitate sludge. The precipitate sludge will be processed using a retort oven for drying and mercury recovery, and then refin ........