Anomalous orebody within the Ambrosia Lake trend at Sandstone Mine

The Sandstone Mine contains an anomalous orebody that lacks the characteristic coloring and high gamma-ray expression typically associated with uranium ore in the Ambrosia Lake district. The orebody occurs at the downdip edge of a tongue of hematitic sand in the basal sand unit of the Westwater Canyon Member of the Morrison Formation. The orebody ranges from white to light gray in color. Preliminary analysis indicates the presence of uranophane (Ca(UO/sub 2/)/sub 2/SiO/sub 3/(OH)/sub 2/.5H/sub 2/O), evidently altered from coffinite, which is the predominant uranium mineral in the district. Equivalent U/sub 3/O/sub 8/ indicates that this orebody is relatively recent. Oxidizing meteoric water, which formed a geochemical cell, remobilized uranium minerals in preexisting trend orebodies and deposited the uranium downdip of the furthest extent of this cell. Post-Dakota deformation influenced the course of the migrating meteoric water and the extent of the redox interface controlling the orebody. As sampling and mining lower grades of uranium becomes increasingly more economical, the potential for unknown reserves adjacent to the redox interface should not be overlooked.