The Hycroft deposit is a low-sulfidation, epithermal, hot springs system that contains Au and Ag mineralization. Radiometric dates of adularia (potassium feldspar) indicate that the main phase of Au and Ag mineralization formed four million years ago (Ebert, 1996) when hydrothermal fluids were fed upward along high angle, normal faults. Low-grade Au and Ag mineralization was co-deposited with silica and potassium feldspar throughout porous rock types. A subsequent drop in permeability, due to sealing of the system, led to over pressuring and subsequent repeated hydrothermal brecciation. Additional precious metal mineralization was deposited during this event as breccia zones, veins, and sulfide flooding. Au and Ag mineralization was followed 0.4 to 2.0 million years ago by an intense event of high sulfidation acid leaching of the mineralized volcanic rocks coincident with a regional water table drop. This allowed steam heated sulfur gases to condense into sulfuric acid and leach the upper portion of the mineralized rocks. Oxidation of sulfide mineralization occurs to variable depths over the deposit, depending upon proximity to faults, extent of acid leaching, and depth to water table. Sulfide content through the deposit is variable from 0% to 20%. 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 Hill. The boundaries are typically major fau ........

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:
- Oxi ........

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