Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
th
, 2014
10135-200-46 - Rev. 0
7-6
affected by widespread potassic alteration and have a thick near
‐
surface
oxidized/weathered zone.
Geological events that can be interpreted in the core of the complex include multiple
intrusions of dominantly porphyritic phonolite and trachyte, multiple brecciation events,
carbonatite magmatism, alkali
‐
ferric iron metasomatism (fenitization), hydrothermal
alteration, and supergene oxidation. Pre
‐
intrusion, syn
‐
intrusion, and post
‐
intrusion
faulting and deformation disrupt the geology, although displacements appear to be
relatively small. Soil and alluvial cover is extensive. Surface rock exposure in the
complex is probably on the order of five percent or less, which further complicates
interpretation of the geologic and hydrothermal history. Major structural trends are
oriented west
‐
northwesterly, northwesterly (parallel to the elongation of the complex),
and northeast or east
‐
northeasterly. The complex plays host to a variety of
mineralization types, including gold (Au), lanthanides (rare
earth elements), base
metals (copper/Cu, lead/Pb, zinc/Zn, and molybdenum/Mo), and thorium (Th). Intrusive
rock types, mineralization, and alteration patterns share many features with the
Cripple Creek complex in Colorado.
Major intrusive rock units listed in approximate order from youngest to oldest units
include the following:
Carbonatite: Carbonatite intrusions range from microveinlets up to dikes approaching
80 feet (24.4 m) in width. They are encountered primarily in drill core, except for the
outcrop on Carbon Hill, and represent one of the latest igneous intrusive events in the
district. Drilling data indicate that the dikes most commonly strike northwesterly and
dip steeply to the southwest or northeast. The carbonatitic rocks can be classified as
either sovite (calcitic carbonatite) or silicocarbonatite.
Sovite: Sovite consists of fine to coarsely crystalline calcite, with a range of essential to
accessory minerals that may include biotite, K
‐
feldspar, apatite, clinopyroxene,
strontianite, dolomite, barite, celestite, sulfides, Fe
‐
Ti oxides, and REE and thorium
minerals. Sulfide and oxide minerals may include pyrite, pyrrhotite, chalcopyrite,
specularite, galena, sphalerite, rutile, ilmenite, and molybdenite, and total sulfide
abundances (mostly pyrite and pyrrhotite) range from trace amounts to 30 percent.
Fluorite is very rare in carbonatites.
Silicocarbonatite: Silicocarbonatite is carbonatite with 30
‐
50% silicate minerals. In the
Bear Lodge district silicocarbonatite contains calcite with significant biotite or
phlogopite and K
‐
feldspar ± accessory aegirine, apatite, strontianite, barite, celestite,
