NI 43-101 Technical report, Surface diamond drilling ... - Iamgold

R a r e E a r t h E l e m e n t E x p l o r a t i o n P r o g r a m M a r c h - 2 0 1 3
W i n t e r - S u m m e r 2 0 1 2 P a g e | 99
• Up to 9,398 original assay data from the ICP table in variable length but mostly 1.5m;
• 3,126 5m composites including all drill holes intersecting the REE Zone;
• 2,871 5m composites for 1985 to 2011 drill holes exclusively;
• 1,672 10m composites including all drill holes intersecting the REE Zone.
Because the drill hole samples in the REE Zone vary in length, it was deemed valid to group
samples in equal length. Composites of 10 metres appear to be a good choice according to
the geology, the sampling statistics and the variography. The final length of 5 metres was
retained after looking at different block models section and plan views. Composites of larger
size smooth the data. Five metres equal length composites appeared to be a better choice
than the 10 metres composites to preserve a certain level of details in the grade model. No
top grade capping value was used before or after compositing. This can be done dynamically
during interpolation in Gems.
The 2011 composites parametres were applied to the data set used for the 2012 block model.
The data set is formed of 7,110 of 5 metres composites including 2011 and 2012 drill holes
intersecting the REE zone (Table 15). The 2011 samples were principally of 1.5 to 2 metres
long and the 2012 samples were uniformly set at 3 metres long. An equal length composite
of 5 metres was judged appropriate to keep a detailed grade distribution in the model.
Table 19: Composites statistics summary used in 2012 resource estimation.
5 m Composites statistics 2012-12-31
Number of samples 7,110
Minimum (% TREO) 0.02
Maximum (% TREO) 8.17
Mean (% TREO) 1.69
Median (% TREO) 1.72
Variance 0.71
Standard deviation 0.84
Coefficient of variation 0.50
19.1.1.4 Variography
The variography is used for the 2012 rare earth elements resources estimation. It was made
for the reported total rare earth oxide (TREO). A standard approach was used to generate and
model the variography. The following steps were followed:
• Orientation and the dips examination of the solids representing the REE zone to
determine the continuity axes.
• Generated and model the down hole correlogram, witch determine the nugget effect
(closed space variability).
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