Lemhi County


  • Fermi has 52 unpatented mining claims totaling 1,070 acres in a uranium-bearing tertiary basin.
  • Uranium occurs as basal-type occurrences in channel-filling deposits of carbonaceous and mudstone.
  • The target area is 100% Bureau of Land Management supervised ground.
  • Regional historic drilling indicated the presence of uranium roll-front occurrences.
  • The geology of the area is conducive to roll-front uranium deposits. Extraction via in-situ recovery methods would be cost effective.


Location & History

The Ellis Project is situated in Lemhi County, Idaho, 16 miles northeast of the town of Challis and 42 miles southwest of Salmon, Idaho.  The project consists of 52 Federal unpatented lode mining claims totaling approximately 1,070 acres.  The geology of the Ellis Project has not been mapped in detail, but is situated in the western pediment of the Lemhi Mountains, a high-relief range in central Idaho.

The original uranium exploration boom of the 1950’s brought exploration to the uranium-thorium veins in Custer County, and alkalic complexes in eastern Lemhi County.  By 1971, roll-front type uranium deposits were being developed in Wyoming, and interest in uranium deposits moved toward central Idaho.  According to Howland’s 1973 report, the only reference available, the Union Pacific Uranium Prospect located 40 miles southwest of the Ellis Project and drilled by Union Pacific Minerals, generated considerable interest in the region.  By 1978, Exxon had staked the Ellis Prospect claims over what is now the Ellis uranium project.  All exploration and drilling are historical and are only described in Howland’s 1973 report.

The Ellis Prospect area is known by several uranium-bearing prospects: one located directly above the Ellis townsite to the east; another, called the Hamilton Prospect, is located to the east; and a southern prospect about 0.75 miles southwest of the Hamilton, which is known as the Nest-Egg Magnum prospect. See photo, below:

Ellis uranium project with surrounding projects.

Geology & Mineralization

The three most important aspects of the local geology are:

  1.  The underlying Tertiary-age structure of the northern Pahsimeroi Valley
    The Pahsimeroi Valley is comprised of unconsolidated fluvial and alluvial deposits shed from the adjacent mountains, glacial deposits, and overbank river deposits. Beneath the permeable Quaternary valley are Tertiary sedimentary rocks, 50-million-year-old Challis volcanic rocks, Paleozoic sedimentary rocks, and Precambrian metasedimentary rocks.
  2. The uranium endowment of the Challis volcanic rocks
    The Challis volcanics are potash-rich, cal-alkaline rocks and in general, are not known to be enriched in uranium. However, numerous highly differentiated silicic intrusions that acted in part as feeders to the enclosing phases of Challis volcanism are rich in uranium and thorium.  These intrusions range from rhyolite to granite, and from plugs, domes, dikes, and stocks to batholiths.
  3. The Quarternary alluvial development in the Valley from west-draining topography of the Lemhi Range
    The unconformity at the previously-mentioned Quarternary alluvium/bedrock contact is the targeted formation for uranium mineralization on the Ellis Project, with the Challis Volcanics being the source rock.


Fermi Uranium Corp. maintains 52 unpatented mining claims for the Ellis Project:

  1. Ellis Claims (52)

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