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 | 98
Between 1968 and 1985, the carbonatite hosting the REE Zone was discovered and studied
using various means, including drilling, airborne and ground geophysics, mapping, bulk
sampling, petrographic and mineralogy studies, etc. Some 22 shallow surface drill holes
were assayed for REE, some sporadically (1968 to 1978), some systematically (1985) and 18
drill holes reported an REE Zone intersect. The original hand written drill logs (in PDF)
reported values for La2O3 only (to represent the REE group) in the first 15 drill holes (1968
to 1978). The 3 drill holes from 1985 report 22 assays, including the major REE. All
available data were captured into Gems database.
All historical drill holes compared favorably to the 2011 and 2012 drilling results. Most of
this data, especially from the period of 1968 to1978 does not have the QA/QC support to
comply with the NI 43-101 standards but there is no evidence that it would not comply with
it. The historical data deemed to match the geology and the new grade data available. In
fact, it made little difference whether it was used or not. It made no difference in the grade as
the old data is completely surrounded by new data. Since new data has been acquired in
2012, the historical data (1968 to 1985) were put aside to favor a more uniform quality of
data. The following table summarizes the database tables and fields used in the resources
estimation at the 31 st of December.
Table 18: Statistics summary of the original assay intervals used in the 2012 resource estimation.
Samples statistics 2012-12-31
Number of samples 15,973
Average length (m) 2.21
Minimum (ppm TREO) 89.82
Maximum (ppm TREO) 123403.10
Mean (ppm TREO) 17106.96
Median (ppm TREO) 16611.10
Variance 91535769.77
Standard deviation 9567.43
Coefficient of variation 0.56
19.1.1.3 Composites
Compositing is a set of techniques to split, group and regroup existing samples to make them
“even” and ready for the interpolation process on a regular 3D grid, the block model.
Drilling and sampling is not even. It is done on line, sections and levels where the access is
available to take the samples most efficiently. Drilling is also a process to discover the shape
of a mineral resources and increase the detail as the exploration program is going on. For the
interpolation process of assigning a grade value to each block, the blocks and the samples
must have a matching rock type.
For the estimation of the REE Zone mineral resources in 2011, several sets of data were
tested against several geological models (Lafleur, P.-J., 2012). Those are:
3400, chemin du Columbium, St-Honoré-de-Chicoutimi, QC G0V 1L0 Canada – tel. : 418 673-4694 Fax : 418 673-3179
E-mail : info.niobec@iamgold.com www.niobec.com