Cathodoluminescence imaging and spectrometry of a jadeite microbeam reference crystal: Detection of Ce3+

Options for selecting a high Na concentration mineral for instrument calibration that are suitably stable under the electron beam are limited [1]. NaCl (approximately a mass fraction of 39 % Na) is not practical for use alongside other embedded and polished materials in a mounted block of standards. While albite (NaAlSi₃O₈; approximately a mass fraction of 8 % Na) represents a typical choice for some microanalysts, it may be subject to time dependent signal intensity issues, such as those observed for Na and other cations during analysis of hydrous glasses [2]. Near endmember jadeite pyroxene (NaAlSi₂O₆; approximately mass fraction of 11 % Na) represents a desirable option for calibration given its relatively large concentration of Na and insensitivity to electron beam radiation with respect to X-ray output. Despite these desirable characteristics, jadeites have been shown to contain complex microstructures as the result of intracrystalline zoning [3, 4], and the impact of chemical inhomogeneity within mineral standards and natural glasses has been documented [5-7]. In this study, a commercially obtained jadeite crystal (source location “China”) was studied to assess its microscale uniformity using a suite of microbeam methods, including dispersive red-green-blue multispectral cathodoluminescence imaging (CL_RGB), hyperspectral CL imaging spectrometry, energy dispersive X-ray spectrometry (EDS), SEM-based micro-X-ray fluorescence (μXRF), and wavelength dispersive X-ray spectrometry (WDS).