Deposit Types
Mineralization in the Gold Bar District has most of the characteristics of Carlin-type gold deposits described in Muntean and Cline (2018), including: carbonate host rocks, tectonic setting, structural and stratigraphic ore controls, hydrothermal alteration consisting of dissolution and silicification of carbonate and argillization of silicates, auriferous arsenian pyrite, a geochemical signature containing Au-As-Hg-Sb-Tl, low Ag (Ag/Au<1), and lack of clear relationship with intrusions. Most Carlin-type deposits are located along long-lived, deep crustal structures inherited from Late Proterozoic rifting and formation of a passive continental margin. They are hosted in a Paleozoic carbonate sequence (lower plate) that is either structurally overlain by a siliciclastic sequence (the Roberts Mountains Allochthon or upper plate), or stratigraphically overlain by a siliciclastic sequence deposited on the carbonate sequence (Overlap Assemblage). Gold mineralization in the Gold Bar district is localized at the intersections of a complex array of structures with permeable and reactive strata. Carbonate dissolution, argillization of silicates, sulfidation of ferroan minerals and silicification of limestone characterize the alteration assemblage related to the main stage of mineralization. Gold is found as sub-micron inclusions or solid solution in arsenian pyrite. Oxidation has liberated gold from the original pyrite, making it amenable to cyanide leaching. Common trace elements include arsenic, antimony, thallium,and mercury.

Central Nevada is underlain by Paleozoic sedimentary and volcanic rocks which were in turn covered by Tertiary volcanic rocks and sediments. During the early Paleozoic, this part of Nevada was the western pre- continental margin of the North American plate. From Silurian through Devonian time, extensive carbonate platforms developed along the continental margin, generating a thick wedge of carbonate sediments to the west as the basin subsided. Farther to the west in deep water, shale, chert and sandstone (siliciclastic rocks) were deposited during that time.

Within the Gold Bar North (GBN) area, three gold deposits have been defined: Gold Pick, Gold Ridge and Cabin Creek. Mineralization in Gold Pick has a strike length of over 4,000 ft with a width of 1,600 ft and thickness of 100 – 150 ft. Gold Ridge and Cabin Creek are ancillary deposits comprising together approximately 22% of the mineral resource. All defined mineralization lies within 500 ft of surface in oxidized carbonate host rocks.

There are two structural blocks in the district, separated by the regionally extensive RMT. Deep-water shale and chert, known as the Vinini Formation (upper plate) were pushed eastward onto the carbonates (lower plate) along the RMT. Late-Paleozoic clastic sedimentary rocks were deposited on both upper and lower plates. Younger (post-Permian) lowangle faulting locally placed lower plate rocks on top of both the upper and lower plates. Tertiary extension resulted in the complex basin and range high-angle block faulting that defines the range today.

SIGNIFICANT MINERALIZED ZONES
Gold Bar North
The Gold Pick, Gold Ridge and Cabin Creek deposits are found in the McColley Canyon Formation.

Mineralization is controlled both by stratigraphy and by overprinting structures. Much of the mineralization in all three deposits is at an orientation that mimics bedding and probably represents favorable permeability in certain debris flow subunits that were selectively more receptive to gold deposition. At Gold Pick East this bedding orientation is N50°E, 23°SE, at Gold Pick West it is N07°E, 24°E, at Gold Ridge it is N20°E, 20°SE and at Cabin Creek it is N01°E, 27°E.

Mineralization also tracks a strong northeast-southwest fabric that is supported by structures identified during surface mapping. These southwest-trending structures are at moderate to steep angles (45-70°NW). At Gold Pick East, the high-angle structures focus grade along on N245°E, 45-60°NW. At Gold Ridge, the orientation is N265°E, 70°NW. The highest gold grades in the deposit are concentrated along these structures likely at the intersection with low-angle stratiform mineralization.

All of the mineralization found to date at the GBN occurs as sediment-hosted, “Carlin-type” gold deposits. The deposits are hosted in carbonate-rich sedimentary rocks of the Devonian Nevada Formation and are characterized by micronsized gold and a distinct hydrothermal alteration suite.

If the term “Carlin-type gold deposits” is used in its strictest sense, the deposits are restricted to a small part of the North American Cordillera in northern Nevada and northwest Utah. Most such deposits are located along long-lived, deep crustal structures inherited from Late Proterozoic rifting and formation of a passive margin. They are hosted in a Paleozoic miogeoclinal carbonate sequence that is either structurally overlain by a eugeoclinal siliciclastic sequence (the Roberts Mountains Allochthon), or stratigraphically overlain by a miogeoclinal siliciclastic sequence deposited in the resulting foredeep (Overlap Assemblage). Gold mineralization is localized at intersections of a complex array of structures with permeable and reactive strata. Carbonate dissolution, argillization of silicates, sulfidation of ferroan minerals and silicification of limestone characterize alteration related to the main stage of mineralization. Gold is found as micron inclusions or solid solution in arsenian pyrite. Common trace elements are antimony, thallium and mercury.

Gold Bar South
The lower 100-200 ft of the overlying Mississippian Webb Formation (siltstone, mudstone), hosts the bulk of the GBS (Gold Bar South) gold mineralization.

The most economically prospective mineralization at GBS occurs at the crest of an east-tilted doubly plunging anticline, interpreted from consistent Devils Gate – Webb Formation contacts recorded in drill logs. Overall the anticline is tilted, with a steeper 25° dipping east limb and a flat west limb. The anticline plunges north at approximately 10° and plunges steeper to the south at approximately 20° before it is ultimately covered by deep basin-filling alluvium.

Mineralization occurred at the base of the Webb Formation and was subsequently offset by a series of east-side-downstepping northeast and northwest-trending normal faults. Mineralization is rarely preserved along these high-angle faults, though undoubtedly some of them served as conduits to fluid flow during the gold event. Locally, normal faulting has created small grabens, in which the thickness of mineralization appears to be enhanced. There is evidence, by reconstructing grade trends of some left- lateral oblique slip on northeast-trending faults, especially in the southern part of the deposit. Lastly, and similar to Gold Bar North, there appears to be some “ponding” of mineralization in troughs of the Devils Gate – Webb Formation contact. These are interpreted as potential karst dissolution zones or debris flows with enhanced permeability.

Gold mineralization at GBS was deposited in brecciated siltstones of the Webb Formation, at and immediately above its contact with the Devils Gate Limestone. Lesser, but important amounts of mineralization occur in the adjacent Devils Gate Limestone as well. Mineralization in GBS consists of epithermal, disseminated, sediment-hosted gold, in zones related to hydrothermal dissolution in limestone and the resulting collapse breccia in the overlying siliciclastic unit. Gold is associated with brecciated, oxidized, silicified, and argillized mudstones, siltstones, and sandstones of the Webb Formation and is usually accompanied by silicification and strong barite veining. Jasperoid along the trace of the fault is brecciated and contains veins of barite and scattered gold mineralization.

The Gold Bar Project is planned for production using conventional hard rock open pit mining methods. Ore production to the crusher is planned at a maximum capacity of 7,500 tpd (2,750 ktons/yr). Additional run of mine (ROM) material will be placed when available. The maximum ore production to the leach pad (crushed & ROM) is planned to be 8,880 tpd (3,240 ktons/yr). The mine production schedule was developed with the goal of filling the crusher at the required ore rate and maximizing the project return on investment. The total material rate is tied to equipment productivity and fluctuates by period. The maximum total production is expected to reach a rate of 43,000 tons/day (16,100 ktons/yr). The mine is scheduled to operate 6 days/wk with two, 10-hour shifts/day.

The Gold Bar Project is currently being mined by a contractor, and this is planned to continue. Contractor equipment on hand is often variable. There is flexibility in the fleet size, and the actual mining fleet in use will likely vary depending on the contractor’s fleet on hand.The schedule and production requirements were based on the following fleet assumptions: Bench heights are planned at 20-ft; drilling is planned based on using four rotary down-the-hole hammer drills with 45,000 lb pull down capacity and 6.75 in diameter blast holes; and the blasted rock will be loaded into 100-ton haul trucks using three, 16-cubic yard front-end loaders.

The mine plan was developed with a phased approach. The phase designs, mine schedule, and mine equipment requirements are summarized in this section.

Gold Bar is a low-grade, disseminated gold series of deposits with mineralization close to the surface at an average remaining head grade of 0.025 oz/t Au.

The phases were tabulated from the mineral resource block model and those tabulations were used as input to the development of the mine production schedule.

Waste rock will be stored in several waste rock facilities designed in close proximity to each pit to reduce haulage costs. Whenever possible, pit backfilling will be utilized if doing so proves to be economic during operations. Some waste mined late in the mine life will be placed in a designated storage facility to meet closure requirements.

The crushing and stacking circuits are designed for 480 dry short tons per hour (stph), with operations scheduled for 24 hours per day, seven days per week, 350 days per year. At an expected 70% operating availability, this will result in placing an average of 8,057 stpd onto the heap leach pad, equivalent to 2,820,000 tons per year.

Ore will be trucked from the mine to either a stockpile close to the primary crusher and subsequently reclaimed with a front-end loader (FEL) or hauled directly to the heap leach pad depending on the grade. The FEL will dump ore into a surge bin. A vibrating grizzly feeder will draw ore from the surge bin, with the feeder oversize reporting to a jaw crusher. The grizzly feeder undersize material will bypass the crusher and will combine with the crusher product on the primary discharge belt conveyor.

The crushed ore will be transferred to the leach pad via an overland conveyor that discharges on to a series of several mobile ramp conveyors and mobile grasshopper-type conveyors. Units of mobile conveyors and grasshopper-type conveyors will be added or removed as required, dependent upon the stacking location on the pad. The final conveyor will be a radial-type mobile stacker that will place agglomerated ore in lifts, up to 25 feet in height. As multiple lifts are placed, the edges of the heap will be concurrently reclaimed to a 3:1 slope. This will reduce closure costs and facilitate safer and easier leaching of the slopes.

Agglomeration is no longer anticipated for the ores at Gold Bar North or South. If needed however, the agglomeration drum and cement addition will remainin the circuit following the crushing and prior to the conveying system. The grizzly undersize and the primary crushed ore will be conveyed to a vibrating, inclined screen. Screen oversize (+3 inch) will bypass the agglomeration drum and report to the screening discharge belt conveyor. The undersize fraction from the screen will be conveyed to the agglomeration drum for the binding process. Cement and barren solution will be added on the screen undersize conveyor ahead of the drum. Agglomerated ore will combine with the screen oversize on the screening discharge belt conveyor. The agglomeration drum and all downstream material handling equipment are physically located within the containment of the heap leach pad liner system.

An evaluation of the test work suggests that the processing should be a mix of crushed and ROM ore placed on the leach pad. Further test work is underway to evaluate the optimum size of ore to be placed on the leach pad and the recoveries of those ores. This test work will allow the calculation of the most economic mix of crushed and ROM ores to be processed.

Gold and silver are extracted from mineralized material by either milling or heap leaching depending on, among other things, the amount of gold and silver contained in the material, whether the material is naturally oxidized or not, and the amenability of the material to treatment.

At the Gold Bar mine, precious metal recovery is through conventional heap leaching and adsorption, desorption, regeneration (ADR) technology for metal extraction from crushed and agglomerated ore.

HEAP LEACH PAD DESIGN
The heap leach pad is designed to be constructed in two phases (Phases 1A and 1B) with 4 cells each, for a total of 8 cells. The leach pad and process facilities extend from an elevation of 6,750 ft amsl at the toe of the process ponds to an elevation of 6,980 ft amsl at the northwestern edge of the leach pad perimeter road. The grade of the lined base receiving ore will range from 7 to 8% on the western half and 2 to 4% on the eastern half. In total, the leach ........