Field Portable X-Ray Fluorescence Geochemical Analysis – Its Contribution to Onsite Real-time Project Evaluation

The field portable x-ray fluorescence spectrometer (FPXRF) has evolved to become a unique highly productive geochemical tool over the past 30 years. As with most highly sophisticated technological tools, it is deceptively simple to use, can easily be carried and operated using only one hand and can provide an onsite, nondestructive chemical analysis of about 30 elements ranging in concentration from about 10 ppm to 100 percent in less than minute. Its use is commonly judged by comparing its purchase price against laboratory analyses. However, the real value of the FPXRF goes beyond cost savings resulting from reducing the number of samples sent to a laboratory for chemical analysis. Onsite use of the FPXRF allows an accurate appraisal of a property, rocks, soils, ore grade, drill cuttings, cores, concentrates etc. in real time when and where correct decisions are needed. The use of this onsite FPXRF method has been objectively demonstrated to be three times more cost-effective than conventional methods of collecting judgmental samples for subsequent laboratory analysis. Laboratory analysis is not eliminated but fewer samples are necessary to appropriately document mineralization identified by FPXRF. The FPXRF capability has not yet evolved to a low enough detection limit for effectively determining gold and PGM in the field so indicator elements are used. Near laboratory quality results can be obtained when people using the instrument understand the basic principles of x-ray fluorescence spectrometry, the physical characteristics that control quality and protocols that can be used to enhance the data quality. This knowledge base is quantitatively described in this paper and the relative importance of each is documented by case histories of the onsite FPXRF use.