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Results of diamond drilling and geologic investigation of the Shirley May (Garo) uranium deposit, Park County, Colorado

March 6, 1952

The Shirley May (Garo) uranium deposit near Garo, Park County, Colo., consists of tyuyamunite
and carnotite that occur as disseminations and as fracture fillings in three beds of medium- to coarse-grained
sandstone. The sandstones are in the Maroon formation of Permian age. This deposit was explored by means
of 12 core-drill holes, totalling 2,003 feet.
The deposit is on the northeast flank of the Garo anticline, a local structure that probably is related
to Tertiary tectonic movement. In the vicinity of the deposit the sedimentary rocks strike northwest and
dip steeply. They are cut by numerous northerly-trending faults that have horizontal displacements of as
much as 1,000 feet. The ore minerals tyuyamunite, carnotite, volborthite, calciovolborthite, malachite,
azurite, chalcocite(?) , and an unidentified yellow to dark-red vanadium oxide are restricted to a complexly
faulted area. The ore body that has yielded most of the uranium ore is in the uppermost ore-bearing sandstone
(bed no. 1) and is stratigraphically 50 and 150 feet above the ore horizons in sandstones nos. 2 and 3,
respectively.
The uranium content of samples from the mine workings ranges from 0. 001 to 0. 48 percent uranium;
dump samples contain as much as 2.39 percent uranium. A total of 40 tons of uranium ore, averaging 1.0
percent uranium, was produced in 1919.

Citation Information

Publication Year 1952
Title Results of diamond drilling and geologic investigation of the Shirley May (Garo) uranium deposit, Park County, Colorado
DOI 10.3133/tei277
Authors Verl Richard Wilmarth, L.E. Smith
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Trace Elements Investigations
Series Number 277
Index ID tei277
Record Source USGS Publications Warehouse