Comparison of Field-Portable X-Ray Fluorescence Analyzer and Conventional Geochemical Analysis

A total of 39 rock (hand-sized grab and core) samples were analyzed as part of a geochemical test to compare the quantitative measurements between the field-portable x-ray fluorescence (XRF) analyzer versus conventional geochemical analysis. Samples with variable amounts of sulphides, ranging from massive sulphide to partially mineralized and three certified reference sample standards (MP-1A ore) prepared by CANMET, were used. The study, which was conducted as part of a carbonate-hosted Mississippi Valley-type lead-zinc deposit project, used selected samples from deposits and occurrences of lead and zinc only. Thus, the results of the study focus primarily on these base metals, plus iron, rather than on a more extensive suite of base and precious metal elements.

A portable Niton XL-502S XRF analyzer was compared with conventional geochemical methods, which included total digestion Induction Coupled Plasma - Atomic Emission Spectrometer (ICP-ES) and X-ray Fluorescence (XRF).

The portable XRF analyzer exhibited high analytical precision for the elements Pb, Zn and Fe. When compared with ICP-ES analysis, a linear correlation coefficient (r2) of between 95% and 100% was determined for powdered XRF analysis and an r2 of between 79% and 89% for spot XRF analysis (i.e., random 'spot' analyses directly on the rock and core specimens). Thus, it is concluded that the Niton XRF analyzer produces quick and efficient screening assays and analytical results of greater precision by powdering approximately 10 g of the sample.

Finally, as the portable XRF analyzer technique evolves and a larger suite of elements with lower limits of detection become available, the tool will become more useful in reconnaissance-type fieldwork. It will also have significant benefit in core libraries, especially if real-time core logging coupled with immediate semi-quantitative results is sought.