H2O Content Measurement in Phengite by Secondary Ion Mass Spectrometry: A New Set of Reference Materials. Issue 4 (6th August 2019) - Luisier, Cindy
Abstract : Five new natural white mica reference materials (RMs) were developed for in situ H2 O content analyses by secondary ion mass spectrometry at the SwissSIMS laboratory of Lausanne University, Switzerland. The white mica reference materials cover a large part of the natural muscovite–phengite compositional range and are therefore suitable as reference materials for the analysis of natural rocks as well as individual minerals. The independent H2 O content of the reference materials UNIL_WM1 to UNIL_WM5 was obtained by thermal conversion elemental analyser and corresponds to 4.35 ± 0.02, 4.33 ± 0.03, 4.30 ± 0.07, 4.50 ± 0.02 and 4.42 ± 0.11 (% m / m, ± 1 s ), respectively. SIMS determinations of H2 O content revealed a matrix effect correlated to the FeO content of white mica. The compositional range in FeO of the reference materials that were calibrated for H2 O determination is from 1.13% to 3.67% m / m . No crystallographic orientation dependency was observed at the level of homogeneity of these reference materials. An analytical precision of 0.02% to 0.08% m / m (1SE) is expected for the final uncertainty on measurements of unknown white micas in natural samples. Key Points: Five new natural white mica reference materials (RMs) were developed for in situ H2 O content analyses by secondary ion mass spectrometry. SIMS analyses of H2 O content revealed a matrix effect correlated to FeO content of white mica.