rare earth elements in Wyoming

granite to granodiorite with rapakivi texture, minor
euhedral garnet, and minor iron staining. Through
the early 1940s, 18,600 kg (41,000 lbs) of mica,
1.8 tonnes (2 tons) of beryl, and 39 kg (85 lbs) of
tantalite were produced from two granitic pegmatites
that cut Paleoproterozoic tourmalinized mica
schist and gneiss (Osterwald and others, 1966).
Additionally, Adams and others (1980) found euxenite,
fergusonite, allanite, and cleavelandite within
the Many Values pegmatites, and noted that tantalite
typically occurs as inclusions in cleavelandite.
King and Harris (2002) described this site as an
unverified occurrence. A representative sample of
the Many Values pegmatite (20120911WS-D)
yielded 75.8 ppm niobium (4.5 times crustal abundance)
and 10.3 ppm tantalum (6.1 times crustal
abundance), but no other significant enrichment is
present.
Many Values Prospect Pits, SE¼NE¼ sec. 32
and NE¼SE¼ sec. 33, T. 13 N., R. 78 W.,
Southwestern Albany County
Prospect pits along US Forest Service Road 544,
in the vicinity of the Many Values mine, expose
granitic pegmatites within Paleoproterozoic felsic
gneiss and Mesoproterozoic Sherman Granite
(Sutherland and Hausel, 2005). A prospect pit
about 0.8 km (0.5 mi) east of the Many Values
mine exposes a granitic pegmatite that cuts gneiss;
this pegmatite (Sample 20120911WS-B) is weakly
graphitic and exhibits minor epidote alteration but
is not enriched in any of the REE or other elements
of economic interest. A prospect pit about 107 m
(350 ft) east of the Many Values mine exposes a
pegmatite that cuts Sherman Granite; the pegmatite
(Sample 20120911WS-C) contains 62.7 ppm
tantalum (36.9 times crustal abundance).
southern bighorn and owl creek
Mountains
In the southern Bighorn and Owl Creek Mountains,
as in the Laramie Range and Medicine Bow
Mountains, granitic pegmatites within Precambrian
crystalline rocks are potential hosts for REE and
associated elements. Allanite-bearing pegmatites
are present within Archean gneiss in the southern
Bighorn Mountains (King and Harris, 2002). Archean
gneiss and tonalite in the Owl Creek Moun-
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tains host columbite-tantalite-bearing pegmatites
(Hausel and others, 1985).
Whippet and Zimmerman Mines Area,
SE¼NE¼ sec. 28 and NW¼ sec. 27, T. 40 N.,
R. 93 W., Northeastern Fremont County
Dikes of Archean granitic rocks intrude the margins
of an Archean supracrustal belt in the Owl
Creek Mountains (Thaden, 1980; Hausel and others,
1985). Tungsten, tantalum, beryllium, potassium
feldspar, and lithium were produced from
pegmatites within these Archean granitic rocks
at Whippet mine #8 (Hausel and others, 1985).
Due to lack of time and direct access, the Whippet
Mine #8 was not sampled.
The Zimmerman beryl mine is 0.5 km (0.33 mi)
southeast of the Whippet #8 mine, and targeted a
northeast trending felsic dike (Thaden, 1980; Hausel
and others, 1985). At the Zimmerman mine,
the outcrop is dominated by white granitic rocks,
mostly white to light gray, very fine-grained to pegmatitic
muscovite tonalite with moderate hematite,
epidote, and black tourmaline. One individual
tourmaline crystal was at least 9 cm (3.5 in) long.
The tonalite is banded in places, and exhibits both
modal and size grading (quartz to plagioclase; pegmatitic
to very fine-grained) (Sample 20121011JC-
F). The tonalite is not significantly enriched in any
of the REE, but contains 24 ppm tantalum (more
than 14 times crustal abundance), 122.5 ppm
cesium (more than 64 times crustal abundance), 12
ppm tungsten (nearly 11 times crustal abundance),
and 480 ppm lithium (more than 28 times crustal
abundance). The high concentrations of lithium,
cesium, and tantalum in this pegmatite suggest that
it is an LCT-type pegmatite. If other pegmatites in
the Owl Creek Mountains are mostly LCT-type,
the prospect of REE-enrichment should be considered
relatively low.
Allie (Parlett-Adams) Claims, SW¼NW¼ sec.
12, T. 39 N., R. 88 W., Northwestern Natrona
County
Russell and Devore (1948) reported radioactive
allanite within lenses of granitic pegmatite enclosed
in Precambrian gneiss at this locality. Radioactivity
over the pegmatite lenses was reported to be two to