The Hycroft deposit is a low sulfidation, epithermal, hot springs system that contains gold and silver mineralization.

Regional Geology
The Hycroft Mine is located on the western flank of the Kamma Mountains in the Basin and Range physiographic province of northwestern Nevada. The faults served as conduits of hydrothermal fluids that deposited the Hycroft mineralization.

Local Geology
The deposit is typically broken into six major zones based on geology, mineralization, and alteration. These include Brimstone, Vortex, Central, Bay, Boneyard, and Camel. The boundaries are typically major faults, namely Break, East and Ramp.

Brimstone
The stratigraphy at Brimstone includes up to 100 feet of alluvium, underlain by Camel Conglomerate rocks (0 feet to 400 feet). The Brimstone ore deposit is hosted primarily by Kamma volcanic rocks in the hanging wall of the East Fault.

At Brimstone, the East Fault is a north-northeast striking, west dipping, normal fault with repeated episodes of movement, including approximately 150 feet to 200 feet of alluvial offset. Where exposed in the Brimstone Pit, the fault clearly shows steep normal movement, with slickensides that plunge 80º to 85º. At depth the fault shallows to 45° to 60º and may merge with the Central and Break Faults. Only minor mineralization is noted footwall to the fault zone.

Zones of silicification of limited thickness, oriented parallel to the East Fault, are present in the footwall zone. Alteration extends for 50 feet to 70 feet footwall to the fault, with pervasive silicification and quartz veining dominant.

Drilling has shown that mineralization extends to a depth of over 1,200 ft in the Brimstone Zone. Mineralization thickness (true width) is 200-1,100 ft thick and remains open to the west towards the Break Fault and transitions into Vortex to the south.

Vortex
The upper elevation at Vortex is hydrothermally clay (kaolinite) altered. Acid leaching is less prominent than in Brimstone and is focused primarily along the East Fault. Strong silicification to depths greater than 1,500 feet is due to veining and phreatic hydrothermal brecciation. At least four mineralizing events are present as evidenced by crosscutting vein and breccia relationships.

The mineralization at Vortex is of both vein and disseminated type, with brecciated and altered rhyolite rocks and volcanic clastics acting as favorable hosts.

Oxide mineralization is present at a depth of approximately 500 feet below surface, with sulfide mineralization extending to 2,500 feet below surface. Mineralization thickness (true width) is 1,000 to 1,800 ft thick. Banded quartz veins with both high-grade silver and gold have been noted in core.

Bay and Boneyard
Mineralization in the Bay and Boneyard zones is hosted by gentle, west dipping Camel Conglomerate. Both clastsupported and matrix-supported conglomerate rocks host mineralization. The basal rock type is tuffaceous lake sediments, composed of fine grained clay with minor layers of gravel and conglomerate extending to a depth greater than 1,100 feet. Mineralization is primarily bedding controlled, with the Range and Central Faults as the main feeders.

Gold and silver mineralization is associated with flat lying Camel Conglomerate, above the lacustrine sediments of the Tsg formation. Mineralization thickness (true width) is 20 to 250 ft thick at Bay and 50-300 ft thick at Boneyard. This zone transitions into the upper zone of mineralization at Central. Bay and Boneyard remain open to the north and east.

Central
Alteration along the Central Zone is similar to that of Bay. Acid leach alteration is stronger and more widespread than at Bay and is extensive in the southern portion of the pit. The acid leaching overlies silicified conglomerate rocks, except along the immediate trace of the Central Fault where silicification dominates as the alteration type. Oxidation extends downward approximately 400 feet.

Gold and silver mineralization is associated with favorable stratigraphic horizons in the Camel conglomerate, with an upper and lower zone noted in drilling, separated by a north-south striking, east dipping clay layer. Mineralization remains open to the west, past the Range Fault, and at depth (>1,400 feet). Mineralization thickness (true width) in the upper zone is 50-300 ft thick, while the lower zone ranges from 300-1,200 ft thick, and remains open at depth. The zone mineralization is contiguous to the Vortex and Brimstone Zones to the east, and the Camel/Cut-5 zones to the south.

Camel and Cut-5 Zones
Mineralization in the Camel/Cut-5 Zones is hosted by conglomerate rocks and occurs as both disseminated gold and silver associated with pyrite and marcasite, and higher-grade veins, including silver bearing pyrargyrite veins. Mineralization thickness (true width) is 200-1,100 ft thick, extends to depths greater than 1,400 feet, and remains open at depth. Oxidation extends to depths greater than 200 feet and an area of intense oxidized mordenite alteration is present between the Cut-5 and Camel Zones. Mineralization remains open to the south, west and at depth. To the north, Camel mineralization is contiguous with the lower zone of the Central Zone, while Cut-5 is contiguous with the upper zone. Mineralization is also open to the west of Camel and to the south towards Hades Fault.

OPEN PIT DESIGN
Open Pits were designed by generating Whittle pit shells based on net block values (net smelter returns) and pit slopes recommended by CNI (Call & Nicholas) and Golder Associates. Hycroft designed the final pit with haul ramps, appropriate catch benches, and mining widths. The Hycroft open pit is a large pit, covering an area nearly 3.25 miles long by 1.75 miles wide and reaching a maximum depth of approximately 2,700 feet.

Pit phasing has been designed internal to the final pit limit. Phasing was based on lower revenue whittle shells, access, and minimum mining widths. The purpose of the phasing is to improve over-all economics by mining higher economic margin phases first. In total, 22 individual phases have been designed.

Haul ramps are design to be 120 ft wide, including the safety berm for double lane traffic accommodating 320-t class trucks. A 10% maximum grade has been considered in the final design. Some internal pit phase designs considered single-lane travel and 12.5% maximum grade for a very limited number of benches near the bottom of the phase. All pits are designed to be mined on 40- t high benches with catch benches every bench. Catch bench widths varied from a maximum of 46.20 ft to a minimum of 22.85 ft.

OPEN PIT OPERATIONS
Hycroft mining operations are currently planned for typical truck and shovel open pit mining methods.

The following ore routing is available to each block:
- Oxide Ore - ROM heap leach & ¾” crushed heap leach
- Transitional Ore - ROM heap leach, ¾” crushed heap leach, ½” crushed heap leach
- Sulfide Ore - ½” crushed heap leach.

GEOMECHANICS
Slopes in Argilic and Propylitic alterations have been designed at a 38° inter-ramp slope angle. Acid Leach alteration is completely mined out, not having any significant final pit slopes. Any pit slopes which may remain in acid leach alteration is designed at 41° inter-ramp slope angle. Slopes in Silicic alteration are designed at 50° inter-ramp slope angle.

West of the Break Fault, slope stability is controlled by the strength of the unconsolidated Camel Formation. Overall slope angles in the upper portion of the west wall sectors of the Vortex domain vary from 30° to 38°. Below the 3600 elevation, the inter-ramp slope angle is 50°, as competent silicified rock is present in the wall. There are four slope sectors that define pit slopes west of the Break Fault: WBF-U, WBF-M, WBF-L, WBF-2U.

To the east of the Break Fault, the rock strength improves significantly due to the pervasive silica alteration of the Camel and Kamma Mountain Formations. Pit slopes for these sectors have been designed to an inter-ramp angle of 38 - 50°. There are three slope sectors that define the pit slopes east of the Break Fault: Vortex-1U, Vortex-1L and Vortex-3.

Thinly bedded rhyolite of the ALS is located in the footwall of the East Fault at depth. A 38° inter-ramp slope angle has been utilized for this sector: Vortex-2. A minimum 220-foot buttress (which is mined as one of the final mining phases) in the silicified rock in the hanging wall has been designed to manage the weak ALS unit that is present at the toe of the slope.

The hanging wall of the East Fault is composed primarily of silicified rock of the Camel and Kamma Mountain Formations and is defined by 2 slope sectors: FWEF-1, FWEF-2. Pit slopes for these sectors have been designed to an inter-ramp angle of 45°.

North of the deeper Vortex portion of the final pit are sectors associated with the Brimstone Pit. The highest slope in this area of the pit is the 1,200-foot-high east wall. The slope has been designed at an inter-ramp angle of 45° for this sector, identified as WBRIM. The East Fault will be mined out in this sector, thereby avoiding potential failure associated with the weak fault zone.

The west wall of Brimstone is less than 1,000 feet high. The upper 150 to 200 feet of the wall will be excavated in mine waste dumps. This stacked waste rock has been laid back to 35° degrees, roughly the angle of repose. Alluvium is present below the dumped waste. Inter-ramp angles of 42° have been utilized for this material. Silicified and argillically altered rocks of the Camel Conglomerate occur at depth. North Ramp Fault slopes will be constructed mainly in argillically altered Camel Conglomerate. An inter-ramp angle of 42° has been used for slopes in this sector. Both these wall sections are defined by the slope sector NRF.

The crushing plant is designed to run a nominal capacity of 98,630 stpd to attain the 36 million ore tons per year target. Hycroft has installed one primary crusher, two secondary crushers and two tertiary crushers. The existing facility will be sufficient during the ramp-up period but will require addition of two more tertiary crushers to attain the design capacity. Processing parameters in the following discussions are derived from simulations of the full plant at the design capacity.

Primary Crushing and Crushed Ore Stockpile
Ore will be transported by haul trucks from the mine to the existing primary crusher via a dump pocket with a 960-ton live capacity (3 truckloads). The primary crusher is a 60” x 113” gyratory crusher, with an open side setting of 7 inches and a feed opening of 60 inches. It is powered by a 1000-hp motor.

The crushed ore is discharged via a surge bin to an apron feeder. The ore is then transferred by a stacker conveyor to a coarse-ore stockpile. A belt scale is provided on the stacker conveyor to measure the amount of crushed ore delivered. A self-cleaning magnet is provided to remove any tramp steel before stockpiling.

The coarse ore stockpile has a live capacity of 27,400 tons and a total capacity of 160,000 tons. The live capacity is nominally equivalent to about 6.7 hours of heap leach feed at peak production.

The crushed ore is reclaimed via two reclaim tunnels beneath the stockpile. In the tunnels are identical reclaim lines, each comprising three reclaim feeders (two operating and one standby) and one reclaim transfer conveyor. Each reclaim feeder has a design capacity of 1,359 tph. The crushed ore is reclaimed from the stockpile at a design rate of 2,485 tph per line. Each reclaim conveyor discharges to the secondary crusher feed bins.

Dust suppression units and bag houses are installed to suppress or remove dust generated by dump trucks, crushers and other material handling equipment.

Secondary and Tertiary Crushing
Hycroft Mining currently operates four Raptor XL1300 cone crushers – two standard and two short heads, on secondary and tertiary duties, respectively, for the heap leach operation. The crushers are driven by 1,300-hp motors. Each crusher is fed from a bin through a vibrating screen. The two additional tertiary crushers required by Year 6 would preferentially be Raptor XL 1300 cone crushers for commonality of spares. However, equivalent crushers for other vendors may be considered in the future.

All four existing cone crushers failed on commissioning due to original mechanical design flaws. Recently, the manufacturer has redesigned the mechanisms and replaced the internals of all four crushers.

Coarse ore from the secondary crusher feed bin (500 st capacity) is fed to the secondary screens. The secondary screens are double-deck Ludowici banana screens, 10 ft by 24 ft. The crushing/screening simulations call for 3-inch (75 mm) and ¾-inch (19 mm) apertures for the top and bottom decks, respectively. Oversize materials from the two decks proceed to the secondary crushers while the undersize of the lower deck goes to the final crushing plant product.

The secondary crusher is fitted with a standard medium cavity and operated at a closed side setting of 1-1/8 inches. Coarse ore will be crushed to about 80% finer than 1.57 inches (40 mm). Product of the secondary crushers is then be conveyed to the tertiary crusher feed bin (500 st capacity).

From the tertiary crusher feed bins, the ore is fed to the tertiary screens, which are single- deck Ludowici banana screens, 12 ft by 28 ft, with 3/4-inch (19 mm) aperture screens. Oversize materials comprise the feed to the tertiary crushers. The undersize of the screen goes to final crushing-plant product.

The tertiary crushers are fitted with short-head fine cavities and operated at a closed side setting of 0.55 inch (14 mm). The material will be crushed to about 80% finer than 0.466 inch and become the final installment into the crushingplant final product.

Overall, the product of the crushing plant will have a P80 of approximately 0.5 inch (12.7 mm). This size distribution will be characteristic of the material that is stacked on the heap.

The final crushed ore product will be conveyed towards the heap leach facility, either to a stockpile or directly loaded to trucks, which will transport the ore to the heap. A conveyor stacking system is planned to operate in Year 6 (2024) of operation.

The heap leach operation is designed to treat three categories of ore:

- Ore Category 1 (ROM ore) – lower grade ore with high cyanide soluble gold is routed directly to the leach pad and cyanide leached to extract gold and silver. This accounts for 4% of the ore over the life of mine. The gold contents are highly soluble and the remaining refractory gold contents are not projected to justify the time and expense of a pre-oxidation step; therefore it will be stacked as ‘ROM’. The ore in this category is typically defined as ‘ROM oxide’ or ‘ROM transition’.

- Ore Category 2 (3/4” Crushed ore) – higher grade ore with high cyanide soluble gold is crushed to a P80 of ¾” and cyanide leached to extract gold and silver. This accounts for 2% of the ore over the life of mine. The gold contents are highly soluble, but additional size reduction is expected to increase gold and silver recovery enough to justify the additional expense. The remaining refractory gold contents ........