EPMA major element data for core and rim compositions of clinopyroxene

The main part of major element concentrations was measured at the Institute of Mineralogy of the University of Hannover using a Cameca SX100 electron microprobe operated through the Cameca PeakSight software. Additional data was generated at the Institute of Geosciences at Kiel University using a JOEL JXA 8900 R electron microprobe. Results from both labs have been cross-checked, analyzing identical samples. All elements have been measured at Kα emission lines with a focused and fixed beam, an acceleration voltage of 15 kV, a beam current of 15 nA, and a signal count time per element of 10s on peak and 5s on each background. Matrix-correction according to PAP. For each of the 39 samples, repetitive measurements on multiple crystals have been carried out. We put a strong focus on reliable primitive core measurements; nevertheless, for most samples, we also acquired data for rim compositions. P-values have been calculated based on a paired, two-sided t-test to evaluate the significance of the difference between core and rim mean concentrations statistically and allow for H0 hypothesis testing. Additionally, propagation of uncertainty has been calculated for Mg# and Ca#.