Grants Uranium District

Region West, Southwest
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area The Grants uranium district produced over 340 million lbs U3O8 from hundreds of mines that developed tabular and roll-front sandstone deposits in the Cretaceous Dakota Formation and the Poison Canyon, Westwater Canyon, Jackpile Sandstone, and Recapture Shale members of the Jurassic Morrison Formation. This focus area includes identified deposits within the Morrison Formation, and the boundaries were also informed by subdistrict maps published by the state of New Mexico (McLemore, 2011). Note that deposits mined from the Todilto Limestone within the Grants uranium district are considered as a separate uranium source area because they are considered a separate mineral system.
Identified resources Identified resources and historical production for uranium.
Production In all, about 340 million lbs U3O8 was produced from the Grants district between 1947 and 2002 (McLemore, 2011). A comprehensive list of mine production is given in McLemore (1983) and McLemore and others (2013, appendix 1).
Status Past mining. Numerous deposits remain undeveloped and some in permitting (see McLemore and others, 2013, appendix 1).
Estimated resources Estimated In-place resources of about 390 million lbs U3O8 are reported by McLemore (2011) for the Grants Uranium District in more than 40 deposits. One of the largest uranium deposits in the United States is Mt. Taylor with about 100 million lbs U3O8 (UxC, 2019), is in the eastern portion of the Grants mineral belt. See McLemore and others (2013, appendix 1) for a list of deposits.
Geologic maps Horton and others (2017), scale 1:500,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Jurassic Morrison Formation, Jurassic Wanakah (Summerville) sandstone, Cretaceous Dakota Formation. More than 90% of the discovered uranium resources are in the Westwater Canyon of the Morrison Formation (McCammon and others, 1986). The V/U ratio is higher in the Salt Wash and Recapture members of the Morrison Formation. Paleo-structural highs may be important in focusing and controlling mineralization (Sanford, 1992).
Deposits Jackpile-Paguate (MRDS dep_id: 10090123), Windwhip, Woodrow mine, Cebolleta-Grant, San Antonio Valley, Marquez Canyon, Bernabe-Montaro, and numerous others.
Evidence from mineral occurrences MRDS; International Atomic Energy Agency (2020b); U.S. Environmental Protection Agency (2006).
Geochemical evidence Unknown.
Geophysical evidence Unknown.
Evidence from other sources McCammon and others (1986) estimated a U endowment of 2.6 x 106 tonnes of U3O8 in the Westwater Canyon Member of the Morrison Formation in the San Juan basin, the southern portion of which includes the Grants mineral belt. Following a spike in short-term U prices in 2007, and attracted by the large in-place resource, the Grants mineral belt was actively explored by a large cast of characters including Uranium Resources Inc., Energy Fuels Inc., Laramide Resources, Uranium Energy Corporation, enCore Energy and others. Work was largely to expand resources near known mineralization and test for potential in situ mining.
Comments Drill core at NMBGMR.
Cover thickness and description Most mines and deposits are at the surface or shallow (<500 ft depths).
Authors Susan Hall, Virginia T. McLemore.
New data needs Update and digitize (GIS) ore deposit maps by McLemore and Chenoweth (1991) that delineate ore deposits mined and ore deposits remaining to be mined.
Geologic mapping and modeling needs Some maps completed as part of STATEMAP program; digitization.
Geophysical survey and modeling needs None requested at this time.
Digital elevation data needs Lidar complete except for a small portion in the southeast.