Uranophane at the Silver Cliff Mine Near Lusk, Niobrara County, Wyoming
In 1950, the U.S. Geological Survey studied a uranium deposit, previously exploited, at the Silver Cliff mine near Lusk, Wyoming. The deposit consists primarily of uranophane that occurs as fracture fillings and small replacement pockets in faulted and fractured quartzite of Cambrian (?) age. The country rock in the vicinity of the mine is schist of pre-Cambrian age intruded by pegmatite dikes and unconformably overlain by flat-lying Cambrian (?) quartzite. The mine is at the southern end of the Lusk Dome, a local structure probably related to the Hartville uplift. In the immediate vicinity of the mine, this dome is cut by the Silver Cliff fault, which is a north-trneding high-angle reverse fault approximately 1,200 feet in length with a stratigraphic throw of 70 feet. The fractured quartzite has been the locus for the deposition of uranophane, metatorbernite, pitchblende, calcite, native silver, native copper, chalcocite, azurite, malachite, chrysocolla, and cuprite. The fault was probably mineralized throughout its length, but owing to erosion the mineralized zone is now discontinuous. The principal ore body is about 800 feet long. The width and depth of the mineralized zone are not accurately known but are at least 20 feet and 60 feet, respectively. The uranium content of material sampled in the mine ranges from 0.001 to 0.23 percent uranium, whereas dump samples range from 0.076 to 3.39 percent uranium.
- Research Organization:
- Office of Scientific and Technical Information (OSTI), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 989086
- Report Number(s):
- TEI-158; TRN: US201019%%586
- Country of Publication:
- United States
- Language:
- English
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