Quantifying common major and minor elements in minerals/rocks by economical desktop scanning electron microscopy/silicon drift detector energy-dispersive spectrometer (SEM/SDD-EDS)

Abstract

Earth and planetary sciences require extensive microanalyses to quantify most common major and minor elements O, Na, Mg, Al, Si, K, Ca, Ti, Cr, Mn, Fe and Ni in minerals/rocks. With O usually calculated, this is frequently done with expensive electron probe X-ray microanalyzer using a wavelength dispersive method (WDS), and much less so with expensive ground-based scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS). Both instruments are not readily accessible to many scientists though. Here we selected eight natural minerals, containing those elements to various amounts, to test the performance of an economical desktop SEM attached with an EDS consisting of just one 10 mm2 silicon drift detector (SDD). The compositions of the minerals were established by extensive electron probe X-ray microanalyses (EPMA)-WDS conducted under routine analytical conditions. They were used to evaluate the performance of the desktop SEM/SDD-EDS system. The examination shows that under modest analytical conditions it can generate accurate results for those elements, with detection limits (∼0.1 wt%) much comparable to routine WDS analyses. Therefore, economical desktop SEM/SDD-EDS system can be an affordable and widely-accessible instrument for extensive and accurate quantification of those most common major and minor elements in minerals/rocks.

Keywords

• Common major and minor elements
• Desktop SEM/SDD-EDS
• EPMA-WDS
• Minerals and rocks
• Silicon drift detector