Measurement error of chemical composition due to the mineral surface states

Abstract

This study estimates the influence of surface morphology of specimen on actual quantitative analysis results measured using the wavelength dispersive spectrometer (WDS) detector and the energy dispersive spectrometer (EDS) detector. The polishing plane of mineral specimens can yield reliable and reproducible results from the WDS measurement, but the measurement errors become larger with an increase of the surface roughness. On the other hand, the EDS semi-quantitative results greatly deviate from the ideal chemical compositions of minerals regardless of their surface roughness. Since rigorous quantitative analysis of a mineral is based on determining an intensity ratio between a characteristic X-ray peak in the mineral and the same peak in a standard measured under identical operating conditions, the measurement errors of chemical composition occur unless the X-ray intensities can be accurately measured under the identical conditions. Serious measurement errors may bring us to mischaracterized interpretations and erroneous descriptions.