Instrumental neutron activation analysis as an analytical technique for gold exploration

Abstract

Abstract Various methods are described for the analysis of Au and the Pt-group elements (PGE) using different geochemical media commonly collected by the exploration geochemist. The methods described utilize primarily the Instrumental Neutron Activation Analytical technique (INAA) in use at a commercial INAA laboratory. Rocks and soils are routinely analyzed by using a Pb fire-assay preconcentration on a 20-g sample and then analyzing the resultant Ag dore bead by INAA to a detection limit of 1 ppb. Growing rapidly in popularity is the analysis of a 30-g aliquot of sample for 34 elements including Au, solely by INAA. The elements included provide a wealth of information of a geological nature. Due to the very inhomogeneous nature of Au occurring in heavy-mineral concentrates it is imperative to analyze the whole concentrate. The only method which can provide a multielement analysis and still retain the sample intact is INAA. Biogeochemistry using either humus or vegetation as the sample media is rapidly becoming widely used. INAA provides a very sensitive means of determining Au and 34 other elements rapidly and at relatively low cost. These and other methods using the INAA technique for Au and the Pt-group will be described.