NI43-101Pre-Feasibility Study Report - page 127

Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
, 2014
10135-200-46 - Rev. 0
burbankite [
is noted rarely in some dikes.
Ancylite forms
stubby, prismatic crystals that are intimately intergrown with strontianite and minor
barite ± minor bastnasite group REE minerals in hexagonal pseudomorphs after an
earlier REE phase (possibly burbankite).
Ancylite and the bastnasite group REE minerals may occur also as discrete phases
intergranular to the gangue minerals. The gangue mineralogy in the carbonatite is
dominated by calcite, with subordinate amounts of sulfide minerals ± biotite, apatite,
sanidine, barite, and strontianite.
The sulfide minerals are present in amounts from less than 5% (locally less than 1%)
to more than 20% and include pyrrhotite and pyrite ± minor amounts of chalcopyrite,
galena, sphalerite, and/or molybdenite. Pyrite is commonly the most abundant sulfide
phase, although it is not uncommon for pyrrhotite to be the most abundant sulfide.
Sulfides are always unoxidized in this zone. Rare earth grades in the carbonatite can
reach in excess of 10% TREO, although average grades of the dikes are less than
3% TREO.
There are no mining activities planned for the unoxidized mineralization in the near
future, since a mineable reserve estimate and a viable metallurgical process have not
been developed. Current mining plans will leave a buffer of oxidized mineralization
over the unoxidized minerals to prevent oxidation.
7.5.2 Transitional Zone
Directly overlying the unoxidized zone is a narrow, conformable, flat-lying zone,
generally less than 20 feet (6 m) thick, and characterized by carbonatite-style
mineralization with variable sulfides and variable indications of gangue mineral
leaching. Between 10% and 90% of the sulfides are oxidized to limonite. The
transitional zone grades rapidly upward into the oxide-carbonate zone. It occurs at
depths of 500 to 600 feet (152-183m) beneath the surface.
7.5.3 Oxide-Carbonate Zone
The oxide-carbonate (OxCa) zone generally occurs at the base of the oxidized zone,
but may reach the surface in places. It extends to nearly 500 feet (152m) in depth.
The OxCa zone overlies the transitional zone and extends lateral to, or beneath, the
oxidized zone. It is characterized by moderately to strongly oxidized carbonatite, with
less than 10% residual sulfides.
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