Gold mineralization in the main Bullfrog and North Bullfrog sub-districts is characterized as volcanic-hosted lowsulfidation epithermal type. Two styles of epithermal precious metal mineralization are present: 1) disseminated mineralization associated with sulfidation of iron in the volcanic host rocks; and 2) open-space filling quartz and/or carbonate veins, which are controlled by boiling. Pervasive quartz-adularia alteration of volcanic rocks is intimately associated with the disseminated mineralization and is an important ground preparation process for later vein forming events. Epithermal deposits form at shallow depth, from the surface to generally <2 kilometers. Temperatures of formation range between 150 to 300°C. Mineralization at NBP is typical of other low-sulfidation type gold systems in and around the Walker Lane trend such as: Bullfrog, Round Mountain, Rawhide, Aurora, Bodie and Comstock. These deposits commonly contain higher gold grades in vein and stockwork zones surrounded by zones of lower grade disseminated mineralization.

Corvus and previous operators exploring in the northern Bullfrog Hills have defined targets in areas of historic mines or prospects, as well as targets associated with high level epithermal alteration. Mineral Resources have been identified in several areas including: Jolly Jane, Sierra Blanca, YellowJacket, Air Track Hill, Air Track West, and Mayflower.

SIERRA BLANCA
The greater Sierra Blanca area includes the Savage Valley, Sierra Blanca, North Sierra Blanca, YellowJacket, Air Track Hill and Air Track West areas.

Mineralization at Sierra Blanca can be classified into the following styles:
- Early, large-volume, pervasive low-grade disseminated gold mineralization associated with quartz-adulariapyrite alteration.
- Middle, structurally controlled disseminated gold mineralization associated with overprinting illite-adulariapyrite alteration and gold enrichment (NW10, NE30, NE50, NE60, Liberator Faults).
- Late, high-grade gold associated with quartz veins and quartz stockwork veining (YellowJacket Vein Zone).

JOLLY JANE
The Mineral Resources at Jolly Jane consist of the older alteration-style quartz-adularia-pyrite disseminated mineralization. The primary host rock is the Sierra Blanca Tuff, and secondary host rocks include the Savage Valley Dacite, Pioneer Formation, Savage Formation and rhyolite of the North Bullfrog Suite. Mineralization is controlled by a combination of small-displacement, high-angle feeder structures and the highly brecciated Sierra Blanca Tuff. The deposit is largely pseudo-stratabound within the Sierra Blanca Tuff. Minor quartz stockwork veining occurs throughout the Jolly Jane area, but no YellowJacket-style gold-silver enrichment event has been identified to date. All of the current Mineral Resources at Jolly Jane are oxide.

MAYFLOWER
The historic Mayflower mine was developed on en-echelon quartz-calcite veins and stockwork zones along the NWstriking, steeply SW-dipping Mayflower Fault Zone (MFZ).

Vein and stockwork mineralization are proximal to individual fault splays. Late stage black manganiferous calcite occurs as veins and breccia fillings along the mineralized structures. This calcite is mineralized and is thought to be a late vein stage of the waning hydrothermal system.

The proposed mining method is conventional open pit mining. Mineralized material and waste are drilled and blasted, then loaded into 133-t payload haul trucks with ~ 20 m3 bucket capacity wheel loaders. The loading and haulage fleet would be supported by track dozers, motor graders, and water trucks. Waste would be hauled to Waste Rock Management Facilities (WRMF) near each pit. Mill resources would be hauled to the mill stockpile while runof-mine (ROM) resources would be hauled and placed directly on the heap leach pad. Mill tailings would be hauled and placed directly on the heap leach pad and mixed into the ROM material by dozing.

Pit slope designs have been based on an overall 50-degree inter-ramp angle. Preliminary pit slope geotechnical evaluations at YellowJacket (Knight Piésold, 2020) indicated a 58-degree inter-ramp angle with 80-degree bench faces would be stable. Preliminary pit slope geotechnical evaluations have been performed for Sierra Blanca/YellowJacket, for Mayflower (Engineering Analytics, 2013b) and for Jolly Jane (Engineering Analytics, 2013a).

The Waste Rock Management Facilities (WRMF) were based on the current mine plan, which predicts that approximately 206.8 Mt of waste rock will require placement and management. The waste rock would be placed in four WRMFs at an overall reclaimed slope of 3H:1V (18.4°). Approximately 91.5 Mt (YellowJacket, Sierra Blanca and Savage pits) would be placed in the East WRMF, approximately 80.9 Mt (Sierra Blanca pit) would be placed in the West WRMF, approximately 20.1 Mt would be placed in the Mayflower WRMF and approximately 14.3 Mt would be placed in the Jolly Jane WRMF.

The mine production schedule focused on opening the YellowJacket pit to provide the annual gravity mill feed of approximately 1.7 Mt. The other pits were sequenced to provide approximately 11.5 Mt of ROM heap leach resource annually for the first 5 years increasing to 18.7 Mt for years 6 through 13.

The yearly mine production schedule beginning in period -1 through period 13, for a total of 14 years of mining. The schedule was completed monthly for 24 months, from period -1 through period 1, and annually thereafter. The production schedule is driven by the nominal rate of 4,700 t/d (1.7 Mt/y) of gravity mill resource. Peak mineralized material and waste production is approximately 102,000 t/d and occurs in period 3.

The schedule was developed using the pit bench data from the design pits for years -1 (construction and perstripping) through year 5, and LG output data was used for years 6 through 13. Initial mining was focused on the YellowJacket pit in order to meet the gravity mill feed demand of 1.7 Mt per year. Sierra Blanca and Savage pits would begin in period 2 and continue through period 13. The Mayflower pit would begin in period 3 and continue through period 5. The Jolly Jane pit would begin in period 5 and continues through period 9.

The mineralized material would be run through a two-stage portable crushing circuit and conveyed into a fine crushed product bin at a P80 of 19 mm (¾ in). The fine crushed product bin would feed a rod mill with a target product size of 48 mesh.

The run-of-mine (ROM) YellowJacket vein and vein stockwork mineralization, having a particle size of P80 of 84 mm (3.3 in), would be trucked to a stockpile located in the vicinity of the mill. The mineralized material would be rehandled with a front-end loader into a heavy-duty horizontal vibratory grizzly feeder which would feed the primary 30 x 48 jaw crusher. The crushed product would be conveyed to a double deck (6 ft. x 20 ft.) inclined screen. The screen oversize, +25 mm (+ 1 inch) material, would be conveyed to a 300 HP standard Cone Crusher. The cone crusher product would be recycled to the double deck screen. The screen undersize (P80 of 19 mm [3/4 inch]) would be conveyed to two fine material bins. The bins would have a total of capacity of 1,600 tonnes.

The mineralization from the bins would be conveyed on a conveyor belt to the rod mill. The conveyor belt would have a magnet to remove tramp iron and a scale to measure the tonnage to the mill. The 4.6 m diameter x 6.5 m long rod mill with 2,680 HP motor will process 220 mtph of fresh mineralized material at 70% solids. The ground product would be classified on four 1.0 x 1.4 m stack sizer with 5 decks on each screen. The screen aperture would be 500 microns (28 mesh) to produce a product of P80 48 mesh. The screen oversize would be returned to the mill for further grinding.

The processing plan has been divided into two facilities:
- Heap Leach/ADR
- Gravity Mill

HEAP LEACH PAD AND SOLUTION DISTRIBUTION
The mixed ROM mineralization and gravity mill tails would be stacked in lifts averaging 9.1 m (30 ft) high to a maximum of 91.4 m (300 ft) (an elevation of 1,355 m (4,445 ft) AMSL) at a nominal rate of 47,315 tonnes per day.

Dilute cyanide solution would be distributed to the leach pad by three vertical turbine pumps installed in a common barren solution sump. Concentrated cyanide solution (30%) would be added directly to the barren sump, as would antiscalant and freshwater makeup.

The solution would be pumped through an 18-inch distribution pipeline around the toe of the leach pad. The solution would be conveyed to each consecutive lift via a series of 12-inch riser pipes. Seven risers would be installed for Phase 1A, with an additional four risers installed to service the Phase 1B of the leach pad. The av ........