rare earth elements in Wyoming

1977; Love, 1984). REE concentrations are typically
correlated with phosphorus content, due to
an association with apatite. Despite its promise as
a host of REE, the Phosphoria Formation has been
the subject of few REE analyses (King and Harris,
2002).
Hoback, SW¼NE¼ sec. 32, T. 39 N., R. 116
W., Southwestern Teton County
The Phosphoria Formation crops out along US 89,
near the historic town site of Hoback, in extensively
folded and faulted terrain, and was the target of
a phosphate exploration trench (Albee, 1968). The
Phosphoria overlies the Mississippian and Pennsylvanian
Wells Formation and is overlain by the
Triassic Dinwoody Formation. The northeastern
margin of this outcrop is cut by a high-angle fault
that places the Phosphoria Formation in fault contact
with the Wells Formation (Albee, 1968). The
Astoria mineral hot spring is located 340 m (1,100
ft) east-southeast of this outcrop (Breckenridge and
Hinckley, 1978), and indicates that the overall area
may have experienced hydrothermal activity in the
past.
The Phosphoria Formation in this area (fig. 24)
includes the Meade Peak Phosphatic Shale Member
and an overlying, unnamed tan mudstone
interbedded with chert-bearing limey mudstone
(Sample 20121003JC-A). The Meade Peak Member
is composed of black, moderately- to well-indurated,
massive mudstone (Sample 20121003JC-B),
interbedded with black, fissile, poorly indurated
shale (Sample 20121003JC-C). The Meade Peak
Member is about 15 m (50 ft) thick at this locality,
and the overall thickness of the Phosphoria
Formation is about 55 m (180 ft). Bedding within
the Phosphoria strikes 288˚ and dips 21˚ NW. The
upper black shale of the Meade Peak Member is the
most phosphatic unit sampled at this location, with
10.4 percent P 2 O 5 . Significant REE-enrichment is
only observed within the black phosphatic shale at
this location; lanthanum and yttrium are the only
REE enriched greater than five times crustal abundances
(table 21). The black shale is also enriched
in various metals, most notably chromium, nickel,
cadmium, and molybdenum.
61
figure 24. Phosphoria Formation outcrop near Hoback.
A, interbedded black mudstone, black phosphatic
shale, and tan mudstone of the Meade Peak Member,
overlain by interbedded tan limestone and mudstone of
the upper Phosphoria Formation. B, bed of REE-rich
black phosphatic shale, underlain by black mudstone
and overlain by tan mudstone; Sample 20121003JC-C
location.
Crystal Creek Canyon, NW¼SW¼ sec. 34, T.
42 N., R. 113 W., Southern Teton County
Simons and others (1988) reported samples with
up to 700 ppm lanthanum, 300 ppm yttrium, and
31.5 percent P 2 O 5 from the Phosphoria Formation
in the Crystal Creek Canyon area. The Meade
Peak Phosphatic Shale Member of the Phosphoria
Formation does not appear to crop out in this area.
At this location the Phosphoria consists of gray
to tan, extensively fractured limestone and limey
mudstone, with nodules of chert and yellow to
brown, radiating-bladed carbonate crystals (Sample
20121003JC-F). This unit is not significantly enriched
in any REE or other elements of economic
interest.