Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
th
, 2014
10135-200-46 - Rev. 0
14-14
hypothesis that low core recovery implies lower TREO grade appears to be correct for
higher-grade oxide samples above 30% FMR; those samples with recovery below
95% average 12% lower TREO grade than samples with recovery above 95%.
The relationship between grade and low core recovery is poorly defined for lower-
grade samples with less than 30% FMR, and low core recovery is associated with
both higher and lower TREO grades than the high core-recovery samples. On an
overall basis, however, low TREO-grade, poor core-recovery oxide samples average
9% higher grade than high recovery samples.
Samples from the OxCa zone show similar behavior to that of the oxide zone,
although the individual curves are more erratic than those for oxide samples. On an
overall basis, low-recovery, low-TREO OxCa samples average 17% higher grade
than comparable high-recovery samples, and low-recovery, high-TREO OxCa
samples average 9% lower TREO grade than comparable high-recovery samples.
Transition and Sulfide zone samples differ from the oxide and OxCa samples in that
low-recovery, low-TREO samples average 7% lower grade than comparable high
recovery samples, and low-recovery, high-TREO samples average 14% lower TREO
grade.
14.6.5
Potential TREO Bias from Low Core Recovery
Considering the observations in Section 14.6.4, there appears to be a significant
chance that TREO grade is biased low, especially for ore-grade mineralization. This
bias was evaluated further by compiling footage-weighted average TREO grades for
oxide and OxCa samples grouped by %FMR above and below 30%, and by core
recovery above and below 95%. The 30% FMR cutoff was chosen because it
corresponds roughly to the threshold between stockwork-dominant mineralization
(below 1.5% TREO) and vein-dominant mineralization (above 1.5% TREO).
The results of this evaluation are shown in Figure 14.8 and suggest that low-core-
recovery, low-%FMR samples are biased slightly high, and that high-%FMR samples
are biased low, compared to high core recovery samples. When all samples are
combined, however, the apparent bias is very small. The terminology apparent bias
is used here, because it cannot be shown that the bias is an actual bias, rather than
an artifact of some other parameter until large tonnages are mined and compared to
the drill-hole grades. In addition, even if the bias is real, it may be larger or smaller
than shown in Figure 14.8, if the estimate of %FMR is also biased.
