Name of the Mine
Pinyon Plain mine.

Location  
Coconino County, Arizona, in the US.

Mine Owner/s  
US uranium mining and refining company Energy Fuels Inc.

Brief Description 
Pinyon Plain is a fully permitted underground uranium and copper operation in northern Arizona. Potentially, it is the highest-grade uranium mine in US history.

Brief History  
Energy Fuels started processing low-cost Pinyon Plain mine ores in the fourth quarter of 2025. 

Primary Metals/Minerals  
Uranium and copper.

Secondary Metals/Minerals  
None stated.

Geology/Mineralisation  
Parts of two distant physiographic provinces are found in Arizona: the Basin and Range Province located in the southern portion of the state; and the Colorado Plateau Province, located across the northern and central portions of the state. 

Pinyon Plain lies within the Colorado Plateau Province.

The region has experienced volcanic activity since the Pliocene epoch. A number of lava-capped buttes rise above the general landscape, and lava flows cover large areas in the southern part of the district. Faulting has exerted significant control on the geologic development and geomorphic history of the region. 

Major structural features include the Grand Wash, Hurricane, and Toroweap fault systems, all trending generally north to south with an eastern up-thrown side. These faults are topographically prominent and show impressive scarps though other less prominent fault systems exist.

The surface expression of the Pinyon Plain breccia pipe is a broad shallow depression in the Permian Kaibab Formation. The pipe is essentially vertical with an average diameter of less than 61 m, but is considerably narrower through the Coconino and Hermit horizons (24.4 m in diameter). The cross-sectional area is in the order of 6 096 m2 to 7 620 m2. The pipe extends for at least 701 m vertically from the Toroweap limestone to the upper Redwall horizons. The ultimate depth of the pipe is unknown. Uranium mineralisation is concentrated in an annular ring within the breccia pipe.

Mineralisation extends vertically inside and outside the pipe over an estimated 518 vertical metres, but potentially economic grade mineralisation has been found mainly in the collapsed portions of the Coconino, Hermit, and Esplanade horizons and at the margins of the pipe in fracture zones. 

Sulphide zones are found scattered throughout the pipe but are especially concentrated in a sulphide cap near the Toroweap-Coconino contact, where the cap averages 6.1 m in thickness and comprises pyrite and bravoite, an iron/nickel sulphide. The mineralisation assemblage consists of uranium-pyrite-hematite with massive copper sulphide mineralisation common
in and near the uranium zone. The strongest mineralisation appears to occur in the lower Hermit-upper Esplanade horizons in an annular fracture zone.

In the mineralised zone, the uranium mineralisation occurs largely as blebs, streaks, small veins, and fine disseminations of uraninite/pitchblende. 

Mineralisation is mainly confined to matrix material, but may extend into clasts and larger breccia fragments, particularly where these fragments are Coconino sandstone. 

In addition to uranium, copper mineralisation is also found within the Main Zone of the breccia pipe. Typically replacing the matrix material, copper occurs as chalcocite, bornite, tennantite, and covelite. Additionally, lower quantities of silver, zinc, lead, molybdenum, copper, nickel, and vanadium are present and scattered throughout the pipe. 

Reserves  
Total proven and probable reserves as at December 31, 2024, were estimated at 127 685 t grading 0.53% uranium.

Resources  
Total in situ measured and indicated uranium resources were estimated at 37 000 t grading 0.95% uranium as at December 31, 2024. Inferred resources were estimated at 5 000 t grading 0.5% uranium.

In situ copper resources as at December 31, 2024, were estimated at 89 185 t grading 6.5% copper. Inferred resources were estimated at 4 000 t grading 6.5% copper.

Type of Mine
Underground.

Mining Method  
Several mining methods are used based on the size and geometry of the mineralisation. The majority and largest ore zones at Pinyon Plain will be mined by longhole stoping. Narrower mineralised zones will be mined as a single drift using jackleg drills with breasting of the roof and ribs to the ore extents. In some cases, the sill may be blasted and mucked out (termed a floor pull).

Major Infrastructure/Equipment  
Existing infrastructure includes a shaft, a headframe, a hoist, a compressor, surface maintenance shops, employee offices, a water well, an evaporation pond, a  water treatment plant, rock stockpile pads, water tanks and a fuel tank. An existing power line terminates at the site.

Prospects  
Ore mined at the Pinyon Plain mine during the third quarter of 2025 had an average grade of 1.27% uranium, which the company believes is one of the highest-grade uranium mines in US history. 

Contact Details 
Energy Fuels
Tel +1 303 974 2140 
Email info@energyfuels.com
Website https://energyfuels.com/