NI43-101Pre-Feasibility Study Report - page 123

Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
, 2014
10135-200-46 - Rev. 0
7.3.3 Mineralization
The Bear Lodge intrusive complex hosts a variety of mineralization types, including
gold, lanthanides (rare earth elements), base metals (Cu, Pb, Zn, and Mo), thorium
(Th), and uranium (U). The Bear Lodge REE deposits are contained within
carbonatite and carbonatite-related dikes, veins, and stockwork. Gold is generally
associated with potassic alteration that may overlap or halo strong REE
mineralization. Gold may be both structurally controlled and disseminated.
The Bear Lodge intrusive rock types, and patterns of alteration and mineralization,
share many features with the Cripple Creek alkaline igneous complex in Colorado. In
both districts, REEs and Au are spatially related, but the highest concentrations of
REEs and Au are not necessarily coincident. The Bear Lodge REE deposits exhibit a
pronounced zonation between LREE- and HREE-enrichment. The Bull Hill deposit is
enriched in light rare earth elements (LREE), while peripheral deposits at Whitetail
Ridge, Carbon, and Taylor are characterized by relative enrichment in heavy rare
earth elements and yttrium (HREE’s and Y), as well as gold. In the Cripple Creek
deposit, the REE minerals, bastnasite and monazite, are common in gold telluride
veins, while apatite with LREE-enriched rims is common in wall rocks adjacent to the
Au-bearing veins. The Bear Lodge property hosts a significant REE deposit central to
several small peripheral gold mineralized materials, in contrast with Cripple Creek,
which hosts a significant gold deposit and associated minor REE-enrichment. More
detailed descriptions of the geology, alteration, and mineralization associated with the
Bear Lodge REE and gold mineralized material deposits and significant mineralized
zones are provided below.
7.4 Bear Lodge REE Project Geology
The Bear Lodge REE deposits are located in the northern lobe, and near the axis of,
the northwest-trending elongate dome forming the Bear Lodge Mountains. They are
associated with carbonatite and silicocarbonatite dikes, veins, and stockwork that
intrude the Bull Hill and Whitetail diatreme bodies and their host trachyte and
phonolite intrusions. The northwest alignment of
diatreme pipes extends
from Bull
Hill through Whitetail Ridge, to Carbon Hill, and coincides with numerous north- to
northwest-striking alkaline igneous dikes and mineralized zones (Figure 7.3).
Carbonatite and silicocarbonatite dikes intrude diatremes
heterolithic breccias, and
surrounding trachyte, phonolite, and igneous intrusion breccia. They commonly strike
northwesterly to northerly. Within the Bear Lodge REE deposit, the main carbonatite
and silicocarbonatite dikes are generally concentrated within the margins of the
diatreme, with smaller dikes and veinlets extending outward into the adjacent wall
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