Sylvie Demouchy is Research Director at the CNRS, France, and joined the Magmas and Volcanoes Laboratory in 2022. She is a geologist and experimentalist specializing in defects in deep Earth minerals. Nathalie Bolfan-Casanova is Research Director at the CNRS, France, and joined the Magmas and Volcanoes Laboratory in 2003. She is a spectroscopist and experimentalist specializing in the incorporation of water into the deep Earth.