Background

Geochemical data set for silicate rocks are essential for modern petrology. Concentrations of major and trace components in igneous rock sample provide many kinds of information about rock history such as eruption or solidification, magma evolution, magma genesis and source materials as well as petrographical classification. X-ray fluorescence spectrometry for silicate rock analysis has been developed for the last few decades. XRF technique is currently used as standard analytical method to determine the chemical composition of major elements in silicate rocks. Rock analysis which demands high accuracy requires the fusion method to eliminate sample heterogeneity, such as grain size and mineralogical effect, owing to various rock-forming minerals. Conventional fusion method has been dominantly used for determination of major elements in silicate rock because dilution by flux significantly reduces sensitivities of trace elements. Pressed powder method is, therefore, applied to trace element analysis. Since it is not efficient and time-consuming that one sample analysis requires two preparation methods, the low dilution fusion method was developed. The low dilution fusion bead technique is a method to improve sensitivity of trace elements, which enables to determine the concentrations of trace elements accurately and reliably as well as major element determination by XRF. This note demonstrates advanced methods to determine the chemical composition in silicate rocks by XRF.