NI43-101Pre-Feasibility Study Report - page 108

Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
, 2014
10135-200-46 - Rev. 0
6 History
6.1 History of the Rare Earth District
The Bear Lodge Mountains were initially prospected for gold during the late
nineteenth and early twentieth century, with a reportedly short-lived mine and mill in
operation (the Bock Mine). Thorium and rare earth mineralization in the Bear Lodge
Mountains were first discovered in 1949 as a result of uranium exploration activity by
prospectors, and the mineralization, along with some carbonatite occurrences, were
documented by the U.S. Bureau of Mines in 1951. The USBM completed a limited
radiometric survey and a ten-hole drilling program in the area of the rare earth
mineralization in 1950-1951. The exploration activity for uranium during the late
1940s and early 1950s included the excavation of hundreds of bulldozer trenches.
The exploration effort was short-lived, because the uranium grades are very low, and
there were no readily available markets for thorium or rare earths at that time.
In 1972, Duval Corporation acquired the exploration rights to the area by claim
staking, based on the results of a stream sediment geochemical survey. They
initiated an exploration program based on a Climax exploration model for
disseminated “porphyry-type” molybdenum-copper (Mo-Cu) mineralization. This
program continued until the end of the 1977 field season. Duval identified locally high-
grade occurrences of copper and rare earth metals, and low-grade gold
mineralization within an altered syenite-carbonatite alkaline intrusive complex. They
completed 13 diamond drill holes (WBD-1 to 13) for a total of 20,363 feet (6,207
meters), 5 rotary drill holes (WBR-1 to 5) for 765 feet (233 meters), and approximately
42 claim-validation rotary drill holes (DUVR-1 to 42) for 2,105 feet (642 meters).
Duval reported an intercept of 40 feet (12.2 meters) averaging 3.5% copper and 4.7
ounces of silver/ton in hole WBD-5, and many drill holes encountered significant
intercepts with total rare earth abundances that range from 1% to 15% in association
with carbonatite and carbonatite-related intrusive bodies.
Duval recognized that the Bear Lodge property had potential to host an economically
significant rare earth element (REE) deposit, and they brought Molycorp into the
project as an operating joint venture partner in 1978. Molycorp owned and operated
the Mountain Pass rare earth mine in California. From 1978 to 1980, Molycorp
completed 12 diamond drill holes (BL-1 to 12) for a total of 13,618 feet (4,151
meters), 165 claim-validation holes (MOL-1 to 165) for 8,250 feet (2,515 meters), and
soil geochemical, ground magnetic, IP/resistivity, and radiometric surveys.
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