A new Cr-spinel reference material (BL-SP) for in-situ microanalyses

Abstract

This study presents a comprehensive characterization of BL-SP, a potential reference material for in-situ microanalysis of spinel-group minerals. The homogeneity of major and trace elements was evaluated using electron probe microanalysis (EPMA), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), X-ray fluorescence (XRF), and solution ICP-MS. EPMA and LA-ICP-MS results reveal exceptional homogeneity in major elements (Al, Mg, Fe, Cr) and trace elements (Ti, V, Co, Ni, Mn, Zn, and Ga) at the micrometer scale. Bulk analyses conducted by XRF and solution ICP-MS show strong consistency with in-situ microanalyses. A systematic evaluation of peak interferences of Ti Kβ – V Kα and Cr Kβ – Mn Kα in high-precision EPMA trace element analysis for spinel-group minerals demonstrates that, for interference corrections with low degrees, such as Cr Kβ – Mn Kα interference, and Ti Kβ – V Kα interference in low-Ti spinels, the overlapping-peak-correction procedure can effectively eliminate matrix effects in overlap standards. Furthermore, the (L)LIF crystal is identified as optimal for trace V analysis in low-Ti spinel-group minerals, minimizing matrix-related inaccuracies. These findings establish BL-SP as a reliable reference material for in-situ microanalysis of Cr-spinel compositions and address a critical gap in reference materials for spinel-group minerals.