rare earth elements in Wyoming

interaction between oxidized groundwater and
reduced geologic environments. Such deposits are
known sources of uranium (e.g., Smith Ranch
mine, Wyoming) and a silver and copper (e.g.,
Paoli deposit in Oklahoma; Thomas and others,
1991). These geological environments potentially
host other metals as well.
deacon’s Prayer Group claims, sE¼sE¼
sec. 18, t. 32 n., r. 82 W., southern
natrona county
Griffin and Milton (1982) reported 90 ppm
cU 3 O 8 , 250 ppm lanthanum, 70 ppm yttrium,
3,000 ppm titanium, and 300 ppm zirconium
within a coarse-grained to conglomeratic arkosic
sandstone in the basal Wind River Formation. The
area sampled by Griffin and Milton (1982) is located
on private land, but the Wind River Formation
crops out on adjacent public land to the north
(Hunter and others, 2005).
An arkosic, coarse-grained sandstone interbedded
with a cobble- to boulder-conglomerate supported
by a coarse grained arkosic matrix crops out here
on a ridge top that trends about 320˚. Clasts in the
conglomerate are dominantly felsic igneous rocks
but mafic, metamorphic, and sedimentary clasts
are also present. The sandstone hosts large iron
concretions greater than 2 m (6 ft) across (table
18). Rinds on the concretions, 10 to 20 cm (4 to
8 in) thick, are composed of dark brown to yellow,
very coarse-grained, subangular, limonite-cemented
lithic arkose (Sample 20121031JC-C). The insides
of the concretions are tan to yellow, very coarsegrained,
subangular, calcite cemented, limo-
55
nitic lithic arkose (Sample 20121031JC-D). The
interiors of the concretions are not significantly
enriched in any of the REE or any other elements
of economic interest. However, the concretionary
rind (Sample 20121031JC-C) contains 152.2 ppm
yttrium, greater than five times its crustal abundance,
and is weakly enriched in all of the naturally
occurring REE except europium and scandium
(table 18). In addition, the rind contains nearly 63
ppm uranium and 0.094 percent titanium. When
compared to the results of Griffin and Milton
(1982), recent sampling indicates that high concentrations
of REE, yttrium, titanium, and uranium
within the Deacon’s Prayer claim group may be
isolated occurrences.
Phosphate-rich sedimentary
occurrences
Phosphatic shales and mudstones across Wyoming
are potential REE-hosts. Known REE occurrences
are hosted by phosphatic shale and mudstone in
western and southwestern Wyoming, and by phosphate
concretions within black shale in northern
Wyoming (fig. 21).
uraniferous Phosphatic Horizons in the
Wilkins Peak Member of the Green river
formation
Love (1964) identified 32 uraniferous phosphatic
horizons within the Wilkins Peak Member of the
Green River Formation in the Green River Basin.
He also described in detail the lower 32.6 m
(107 ft) of the Wilkins Peak in a measured section
on Lulu claim #2 that includes 13 lithologically
table 18. Concentration of the REE, uranium, thorium, and titanium within the Wind River Formation in the
Deacon’s Prayer claim group. Bold values indicate concentrations greater than five times crustal abundance.
Element La (ppm) Ce (ppm) Pr (ppm)
Deacon’s Prayer group
Nd (ppm) Sm (ppm) Eu (ppm) Gd (ppm) Tb (ppm) Dy (ppm) Ho (ppm)
20121031JC-C 66.1 111.5 13.8 48.1 11.25 1.82 19.35 3.03 18.8 4.11
20121031JC-D 32.1 53.1 6.42 21.4 4.64 0.68 5.23 0.77 4.44 0.85
Element Er (ppm) Tm (ppm) Yb (ppm) Lu (ppm) Sc (ppm) Y(ppm) Cumulative
REE (ppm)
U (ppm) Th (ppm) Ti (%)
20121031JC-C 12.05 1.52 8.34 1.33 12.3 152.5 485.9 62.7 26.5 0.09
20121031JC-D 2.43 0.32 1.91 0.3 7.9 26.2 168.7 35.5 14.6 0.08