Electron Probe Microanalysis measurement of <scp>F‐Cl‐Nb‐P</scp> for Geological Glasses

Abstract

Quantitative in situ electron probe microanalysis (EPMA) was applied to determine the F, Cl, Nb and P contents of glass materials. Using reference glasses with low FeO T (&lt; 10% m/m ) mass fractions to construct a F calibration line to correct the Fe interference on the F peaks, is unsuitable for analysing natural Fe‐rich melt inclusions with up to 21% m/m FeO T , which commonly occur in picritic, nephelinitic and basanitic samples. For this reason, this study presents a series of seven F‐free glasses, which show a wider range of FeO T (1–20% m/m ) that were synthesised to improve the overlap correction of Fe on F. Using this improved method, reference glasses of USGS and glasses synthesised from powders of other rock RMs were analysed to evaluate well‐known reference materials (RMs) as quality control materials for EPMA measurement of F, Cl, Nb and P mass fractions. The results show that amongst the tested RMs, USGS BHVO‐2G is the most appropriate RM for F‐Cl determination because different pieces of this glass RM analysed by different laboratories yielded results that agree within uncertainty.