United States

Alta Mesa Mine

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Mine TypeIn-Situ
  • Uranium
Mining Method
  • Solution mining
Production Start... Lock
Mine Life... Lock
SnapshotThe Alta Mesa Uranium Project is an in-situ recovery (ISR) mining project, and past producer consisting of two distinct properties; the Alta Mesa property, which is composed of the Alta Mesa mine area and processing facility, South Alta Mesa (SAM) and Indigo Snake. The second property is Mesteña Grande, which is composed of Mesteña Grande Goliad (MGG), Mesteña Grande North (MGN), Mesteña Grande Central (MGC), Mesteña Grande Alta Vista (MGAV), and El Sordo.

Phase 1 would include delineation of the PAA7 and PAA8 mineral resource areas. Phase 1 would include some rehabilitation and modernization of the facility and preparation of a Potential Economic Assessment. Phase 2 would include wellfield planning, installation of baseline monitor wells, hydrologic studies and related activities to advance permitting of the wellfields.

Upgrades and refurbishments continue to advance on schedule for the planned 2024 resumption of uranium production.


Boss Energy Ltd. 30 % Indirect
enCore Energy Corp. 70 % Indirect
In February 2023, enCore Energy Corp. acquired 100% of the Alta Mesa Project from Energy Fuels, Inc.

On February 26, 2024, was formed a joint venture company owning Alta Mesa with enCore holding a 70% joint venture interest and remaining the project manager, and Boss Energy holding a 30% joint venture interest.

Deposit type

  • Sandstone hosted


The Project is located in the South Texas Uranium Province, which is known to contain more than 100 uranium deposits which were developed during the 2nd half of the 20th century (Nicot, et al., 2010). Within the South Texas Uranium Province, uranium mineralization is primarily hosted by four formations. Those in order of descending age are the Miocene/Pliocene Goliad Formation, the Miocene Oakville Formation, the Oligocene/Miocene Catahoula Formation, and the Eocene Jackson Group. Within the Alta Mesa portion of the Project, Quaternary formations are exposed at the surface. These are conformably underlain by the Goliad Formation, the primary uranium host. At the Project, in order of importance, uranium is hosted by the Goliad, Oakville, and Catahoula formations. Alta Mesa ISR mine units have exploited uranium mineralization in the Goliad C sands within PAA-1, PAA-2, PAA3, PAA-4, and PAA-6. The B sand was targeted in PAA-5. Within the Mesteña Grande portion of the project, mineralization is also present in the Goliad Formation but is dominantly found in the Oakville Formation. In the western portion of Mesteña Grande mineralization is found in the Catahoula Formation. The nomenclature between Alta Mesa and Mesteña Grande varies with individual sands at Mesteña Grande designated by number, i.e., 10, 20, 30, etc. rather than by letter A, B, C, etc. as they are in the Alta Mesa portion of the Project. Mineral resources have been estimated for all areas within the Mesteña Grande portion of the project. Mineralization within the South Texas Uranium Province is interpreted to be dominantly roll-front type mineralization and primarily of epigenetic origin (Finch, 1996). Roll-fronts are formed along an interface between oxidizing groundwater solutions which encounter reducing conditions within the host sandstone unit. This boundary between oxidizing and reducing conditions is often referred to as the REDOX interface or front. Sandstone uranium deposits are typically of digenetic and/or epigenetic origin formed by low temperature oxygenated groundwater leaching uranium from the source rocks and transporting the uranium in low concentrations down gradient within the host formation where it is deposited along a REDOX interface. Parameters controlling the deposition and consequent thickness and grade of mineralization include the host rock lithology and permeability, available reducing agents, groundwater geochemistry, and time in that the groundwater geochemical system responsible for leaching; transportation and re- deposition of uranium must be stable long enough to concentrate the uranium to potentially economic grades and thicknesses. Typically, the width of the mineralization above a 0.3 GT cutoff is approximately 35 feet. Depth of mineralization at Alta Mesa is in the range of 500 to 600 feet and depth of mineralization at Mesteña Grande is up to 1,200 feet. The oxidation/reduction interface (REDOX), which controls the mineralized trends, is often continuous along several miles. The thickness and grade of mineralization varies. Average thickness above a 0.3GT cutoff, ranges from 4-10 feet with average grade ranging from 0.06 to 0.17 %U3O8. The deposit is a sandstone-hosted roll-front type deposit wherein uranium mineralization is concentrated along the REDOX interface. Uranium mineralization is commonly uraninite (uranium oxide) with some coffinite (uranium silicate). Mineralization tends to be continuous along the REDOX front but varies with respect to width, thickness and grade.



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Mining Methods


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Crushers and Mills

Milling equipment has not been reported.



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All production numbers are expressed as yellow cake.

Operational metrics

Annual production capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe1.5 M lbs of uranium yellow cake1.5 M lbs of uranium yellow cake1.5 M lbs of uranium yellow cake

Production Costs

Commodity production costs have not been reported.


Book Value M USD  ....  Subscribe

Heavy Mobile Equipment

Fleet data has not been reported.


Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jan 3, 2024
....................... Subscription required ....................... Subscription required Subscription required Jan 3, 2024
....................... Subscription required ....................... Subscription required Subscription required Jan 3, 2024
....................... Subscription required ....................... Subscription required Subscription required Jan 19, 2023

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