URANIUM IN UTAH

Utah is the third-largest uranium producing state in the U.S. with a cumulative production of some 130 million pounds of U3O8. Although all Utah uranium production has ceased, Utah still has two of the four currently permitted uranium mills in the U.S.: the operating dual-circuit White Mesa U-V mill near Blanding and the Shootaring U mill at Ticaboo, which is on standby.

The vast majority of Utah's uranium production has come from small, low- to moderate-grade, sandstone-hosted uranium deposits mined underground in the Colorado Plateau, although there has also been minor production from volcanic and volcaniclastic rocks in western Utah. The sandstone-hosted uranium ore bodies are peneconcordant, both tabular and roll front, and typically occur in linear clusters along favorable channels and trends. The Lisbon Valley (Big Indian) mining district is Utah's largest uranium district with nearly 54 million pounds of U3O8 produced. Unmined uranium mineral resources remain at many old Utah properties with the largest known resource being the roughly 20 million pounds of U3O8 remaining at the Bullfrog-Tony M deposits in the Shootaring-Delmonte district of the southern Henry Mountains. Most of the current exploration and development work in Utah is focused on the Lisbon Valley, La Sal, La Sal Creek, and Henry Mountains areas.

The principal sedimentary ore hosts in Utah are fluvial-lacustrine sandstones of the (1) Triassic Chinle Formation, yielding roughly 80% of the uranium ore, (2) the Jurassic Morrison Formation, the leading vanadium producer, and (3) lesser production from the Permian Cutler Formation. The main ore producers in the Chinle Formation are the basal Shinarump Member, which is coarse-grained sandstone, and the Moss Back Member, which is typically cross-bedded, medium-grained sandstone. Whichever of these members is in contact with the underlying Moenkopi Formation is typically the primary ore host in the Chinle Formation. The basal Salt Wash Member is the primary ore host in the Morrison Formation. The Salt Wash Member is fine- to medium-grained, cross-bedded sandstone. The Cutler Formation is a much less important uranium host and is arkosic sandstone where the mineralization is typically uranium-copper.