technical report on the nechalacho deposit, thor lake project ...

CORE LOGGING AND CORE RECOVERY
The REE-bearing minerals in the Nechalacho deposit are generally not visible with the naked
eye due to their disseminated and fine-grained nature. The dominant minerals identified easily
are zircon and (infrequently) traces of bastnaesite although visual grade estimates of
bastnaesite are rarely possible. To map the relative grades in the core Avalon utilizes a
Thermo-Scientific Niton® XLP-522K hand held analyzer for assistance to the geologist while
core logging. The NITON ® energy-dispersive x-ray fluorescence (EDXRF) analyzers, commonly
known as XRF analyzers, are able to quickly and non-destructively determine the elemental
composition of the drill core.
A number of elements may be analyzed simultaneously by measuring the characteristic
fluorescence x-rays emitted by a sample. EDXRF analyzers determine the content of a sample
by measuring the spectrum of the characteristic X-rays emitted by the different elements in the
sample when it is illuminated by X-rays, in the case of the XLP-522K, from a small, sealed
capsule of radioactive material.
Due to variations in analysis conditions – the physical surface of the sample, the dampness of
the sample, and the small window for analysis – the readings for individual elements cannot be
considered as quantitative and representing long core lengths. However, the readings can
assist the geologist to identify mineralized sections, and determine whether these sections are
relatively higher or lower in heavy rare earth elements.
Tests were completed to compare Niton readings for a suite of economically important elements
in Nechalacho drill core to laboratory assays for two metre lengths of drill core. One test
involved 24 readings over a two metre length of drill core compared to the laboratory analyses
for that interval. The second test was to complete between one and four readings per two metre
interval on two drill holes and compare to laboratory assays. Statistics was used to compare the
results from the Niton with the laboratory analyses.
For the test on the one core interval, a one-sample t-test was utilized to compare the Niton
readings to analysis of the interval with the results illustrated in Table 11-1. The one-sample t-
test tests the null hypothesis that there is no significant difference. If the t-test gives a p-value
greater than 0.05 it is taken that there is no significant difference at the 95% confidence level.
As can be seen in Table 11-1, the elements Sm, Nd, Y, Gd and Ce give strong indications of
correlation between the assay values and Niton readings. Nb, La, Dy and Pr give weaker results
and Fe, Eu, Ta, Tb and Th give unacceptable results.
The second test compared Niton readings with one to four per interval over two drill holes, L07-
52 and 61A, which were used to compare laboratory analyses against individual Niton analyses
using a two sample t test and regression for paired samples. This test also gave acceptable
Technical Report 43-101 – March 13, 2011 Page 11-5
Prepared by Avalon Rare Metals Inc.