| Basis for focus area |
More than 100 occurrences and 42 mines are identified in the Todilto Limestone in the Grants uranium district. The focus area includes identified producers and trends along the strike of the prospective Todilto, and is a subset of the Grants Uranium District focus area. Mineralization in the Morrison Formation in the sandstones of the Grants district is of the sandstone/tabular and roll-front types, whereas uranium in the Todilto Limestone precipitated in the presence of organic material within intraformational folds and associated fractures in the limestone (McLemore, 2011). |
| Identified resources |
Identified resources and historical production for uranium. |
| Production |
In all, 6.6 million lbs U3O8 was produced from mines in the Todilto Limestone between 1950 and 1981 (McLemore, 2011). A comprehensive list of mine production is given in McLemore (1983) and McLemore and others (2013, appendix 1). |
| Status |
Past mining. Many deposits remain undeveloped. |
| Estimated resources |
Estimated historical In-place resources of 8.2 million lbs U3O8 are reported by McLemore (2011) from the Saint Anthony Mine, as well as "additional" resources (not quantified) for the F-33, Mesa Alta, Barbara J2 and J3 deposits. See McLemore and others (2013, appendix 1). |
| Geologic maps |
Horton and others (2017), scale 1:500,000; Hackman and Olson (1977), scale 1:250,000; Dillinger (1990), scale 1:100,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Todilto Limestone member of the Jurassic Wanakh Formation-early folds and fractures were mineralized at ~155-150 Ma, shortly after deposition of the Todilto. |
| Deposits |
Ambrosia Lake subdistrict: Barbara Jean #1 (MRDS dep_id: 10151105), Section 4, F-33-Grants Ridge mines; Laguna subdistrict: Saint Anthony mines (MRDS dep_id: 10012282); Coyote subdistrict: Mesa Alta-Yeso mine (MRDS dep_id: 10272612). |
| Evidence from mineral occurrences |
MRDS; International Atomic Energy Agency (2020b); U.S. Environmental Protection Agency (2006). |
| Geochemical evidence |
Unknown. |
| Geophysical evidence |
None. |
| Evidence from other sources |
Recent exploration in the Toldilto area has been reported by JV partners Uranium Energy Corporation and Uran Limited who drilled for potential extensions of the historical F-33, Eagle, Blackhawk, Christmas, Red Bluffs and UDC mines in 2009. Kinti Mining (Cibola Explorations Inc) acquired the Vallejo mine and the Todilto open pit into their Zia project. No in-place resources are reported from either exploration program. |
| 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. |
