The Denton-Rawhide Mine is located within the western portion of the Basin and Range Physiographic Province, an area of northward-trending mountain ranges separated by alluvial valleys. The Rawhide epithermal gold-silver deposit is located along a northwest-trending structural zone that delineates the northeastern margin of the central Walker Lane.

The oldest rocks exposed near the Denton-Rawhide project area are limestone, shale and dolomite sequences that most likely correlate with the Triassic-age Luning Formation. These sequences, referred to as basement rocks by Gray (1996), occur in the Sand Springs Range north and east of the Denton-Rawhide Mine. Drilling around the open pits within the project area has encountered these older rocks to depths of 120 to 800 feet below the near surface volcanics (BLM, 1996)

The rock types within the Rawhide volcanic center have been subject to extensive faulting and hydrothermal alteration. The three primary units within the Mine area are referred to informally as lithic tuffs, andesite, and stratified tuffaceous sediments and volcanic breccias. The lithic tuffs (Tlt) consist of volcaniclastic and pyroclastic rocks 800 to 2,000 feet thick (Gray, 2000). The unit is locally divided into subunits based on textural and compositional criteria. Irregular flows of andesite (Ta), the principal host for bulk mineable ore, overlie the lithic tuff (Tlt). Thickness of the unit ranges from 0 to 400 feet (Gray, 1996).

Unconformably overlying the andesite unit is a sequence of intercalated lithic tuff-breccia with volcaniclastic sandstone and siltstone (Tst). Individual beds of volcanic breccias have been reported to be more than 30 feet thick. The finely stratified pyritic siltstones are interpreted to have formed during subaqueous hydrothermal venting within a lacustrine environment (Black, 1990). This series of tertiary volcanic rocks overlies a rooted flow dome, which is believed to be the top of a cupola of a larger intrusive pluton which has been mapped in the area. This flow dome, described by Gray (1996), is anticipated to be extensive in nature and is observed blanketing much of the area surrounding the Rawhide volcanic center. A magnetic geophysical survey conducted by KRMC identified this arcuate igneous body trending from the Koegal Hills in an east-northeast direction under the alluvium. The presence of this intrusive body would undoubtedly isolate the Rawhide site from the surrounding areas with regard to groundwater flow. Such rocks act mostly as confining units or barriers to flow. Any groundwater present within such a rock unit would exist only locally in the unit where the rock is fractured.

A rhyodacite (Trd), described in Black (1990) as a hornblende biotite rhyodacite, appears to be an intrusive flow dome, and was the ore host at Hooligan Hill. Trd was encountered as intrusive bodies below Murray Hill, Crazy Hill and Rawhide Wash, but appears to be extrusive north and northwest of Hooligan and Grutt Hills (Gray, 1996). The Balloon Rhyolite (Trp) includes intrusive and extrusive rocks in the Murray Hill Pit and in Balloon Hill. Trp is typically bleached white due to alteration. Local mineralization is strongly associated with silica veining and brecciation (Gray, 1996).

The Balloon Rhyolite (Trp) includes intrusive and extrusive rocks in the Murray Hill Pit and in Balloon Hill. Trp is typically bleached white due to alteration. Local mineralization is strongly associated with silica veining and brecciation (Gray, 1996).

A welded, crystal-rich lapilli ash flow tuff (Tlat) sequence crops out extensively to the north and east of the Mine. This unit is rarely encountered within the mineralized deposit (Gray, 1996). The tuff is older than, and may underlie, the Rawhide volcanic center (Black, 1990).

Mineralization at the Denton-Rawhide Mine is highly structurally controlled. Intersections of major fault structures coincide with bulk-mineable mineralization and orebodies are often bounded by faults. Some faults are steep to vertical for considerable depths, which attests to their importance as major plumbing conduits for hydrothermal events. Right lateral strike-slip faulting of the preTertiary basement is manifested as repeated en echelon, north-south striking right-lateral strikeslip faults in the overlying rocks. Major zones of intersection of these faults with northwesttrending faults correlate well with major zones of mineralization. Repeated post-mineral deformation is evidenced by offset orebodies and alluvium (Gray, 1996).

The ore deposit is located within an area of hydrothermal alteration approximately 3 miles in diameter that encompasses most of the Rawhide volcanic center. Two types of epithermal precious metal mineralization have been described at Rawhide. Porous, poorly welded lithic tuffs and volcaniclastic sediments host disseminated ore with pervasive silicification and adularization. Ore in brittle, non-porous host rocks, such as the andesite unit, is more fracture-controlled and characterized by abundant, closely spaced, sheeted to stockwork quartz-adularia veins (Black, 1990).

Gold occurs as electrum in both oxidized and sulfide ore at Rawhide. Silver occurs primarily as embolite and lesser cerargyrite and embolite in oxide ore, and as silver selenides, sulfides and sulfosalts in sulfide ore (Gray, 2000). Fine-grained pyrite is the most common sulfide mineral, comprising 1-5% of sulfide ore. Black (1990) reported that approximately 75-80% of the ore was oxidized.

The Rawhide mine is a fully permitted operation that produces gold and silver through an open pit heap leaching operation. In 2019, Rawhide received a mine expansion permit associated with the Regent open pit. It is surrounded by multiple 1.0 million+ gold oz deposits. [p.28]

Mining in the Regent Pits has an expected life of 3 years and the continued operation of the Main Pit has an expected life of 5 years. Mining of all pits concurrently would continue for a total of approximately 8 years from time of approval of this Proposed Activities. Recirculation on the HLP is anticipated to occur for approximately 5 years. [2018, Amended Plan of Operations, p.43]

Regent Pits
Development of the proposed Regent and East Regent pits would result in a total surface disturbance of 68.4 acres on BLM-managed public land. The disturbance area for the proposed pits includes a 100-foot perimeter berm around each pit. The area between the two pits would include the Regent haul road (5.9 acres) and ancillary disturbance (33.9 acres). Approximately 3.4 million cubic yards (yd3) or 5.3 Mt of ore and 3.5 million yd3 or 5.5 Mt of waste rock would be excavated from the Regent Pit and East Regent Pit combined. Ore would be placed in the previously permitted Western Extension Phase 4 Heap Leach Pad (HLP) and Phase VI HLP, and the proposed Western Extension Phase 5 HLP, proposed T-Bone HLP, and proposed Phase VII HLP. [2018, Environmental Assessment, p.22]

The Regent and East Regent pits would be mined using conventional open-pit mining methods (drilling, blasting, loading, and hauling). The Regent Pit bottom would be excavated to an elevation of approximately 4400 ft amsl and the East Regent Pit bottom would be developed to an elevation of approximately 4500 ft amsl. A Suitable Growth Media (SGM) stockpile generated from removal of any surface alluvium encountered during mining of the proposed Regent Pits would be placed in an ancillary disturbance area between the Regent and East Regent pits. [2018, Environmental Assessment, p.23]

The Rawhide Main Pit
The Rawhide Main Pit consists of a series of connected pits (Murray Hill Pit, Hooligan Pit, Grutt Hill Pit, Balloon Hill Pit, ZZ Tops Pit, North Forty Pit, Crazy Hill Pit, and Crazy Hill South Pit). [2018, Environmental Assessment, p.11]

The Rawhide Main Pit would continue to be mined to a base elevation of 4300 feet above mean sea level (ft amsl). Approximately 2.5 million tons (Mt) of ore and 10.4 Mt of waste rock would be excavated over the remaining life of the Denton-Rawhide Mine. Continued ore production would be placed on the Phase VI HLP or on HLP phases included in the APO. Waste rock would be placed as pit backfill in inactive areas of the Rawhide Main Pit or in the West WRSF or East WRSF. The Rawhide Main Pit would ultimately encompass approximately 315 acres of private land. [2018, Environmental Assessment, p.11]

The Denton-Rawhide mine site consists of heap leach pads (HLP), waste rock storage facilities (WRSF), process ponds, Merrill-Crowe Plant, and Carbon Adsorption-Desorption Refinery Plant.
[Oct 2018 Environmental Assessment, p. 11]

During active mining operations, ore is fed into the three-stage crushing plant at a standard operating rate of 20,000 tons per day. Lime is added to the crushed ore and the material is transported to the heap leach pads via a series of portable conveyors. [p. 38]

Heap Leach Facilities
The existing heap leach facilities consist of a 295.2-acre heap leach pad constructed in several phases, with an additional 17.3-acre pad permitted but not constructed (Phase VI-A1), and a 21.5-acre pad permitted but not yet constructed (Western Extension Phase 4). Process ponds include ten double lined solution ponds and one single lined stormwater contingency pond (the single lined sludge settling pond is included in the discussion of the meta ........