The Silver Reef district is near Leeds, about 16 miles north of St. George, Utah. The major structural feature of the district
is the Virgin anticline, a fold extending southwestward toward St 0
George. The anticline has been breached by erosion, and sandstone
hogbacks or “reefs” are carved from the Shinarump conglomerate and
sandstone members of the Chinle formation, both of Triassic age.
Thirteen occurrences of uranium-vanadium minerals, all within the
Tecumseh sandstone, which is the upper part of the Silver Reef
sandstone member of the Chinle formation, have been examined over
an area about l o75 miles wide and 3 miles long.
Two shipments of uranium-vanadium ore have been produced from
the Chloride Chief and Silver Point claims. Samples from the deposits
contain as much as 0.94 percent U3O8. The ore contains
several times as much vanadium oxide as uranium, some copper; and
traces of silver. It occurs in thinly bedded cross-bedded shales
and sandstones within the fluviatile Tecumseh sandstone member of
the Chinle formation. The ore beds are lenticular and are localized
near the base, center, and top of this sandstone member. The
uranium-vanadium ore contains several yellow and green minerals not
yet identified; the occurrences are similar to, but not associated
with, the cerargyrite ore that made the district famous from 1879 to
1909.
