Mineral and glass geochemical analyses (spot analyses) of samples recovered during IODP Expedition 398 (Site U1595). Site U1595 (proposed Site CSK-08B) is located in the southern basin of the Santorini caldera at 291 meters below sea level (mbsl). It was drilled in three holes (U1595A-U1595C) to a maximum recovery depth of 127.0 meters below seafloor. Some data files also contain SEM-BSE images of volcanic ash particles. Abbreviations used: n.d. = not determined; b.d. = below detection. Detection limits for volatiles in glass: Cl = 57 ppm, F = 140 ppm, S = 56 ppm Mineral and glass geochemical compositions were determined by electron probe micro-analysis, using facilities at the Natural History Museum London and at the University of Leeds. SEM-BSE images were generated at Keele University. Data analysis was supported by NERC - UK IODP Phase 4 Moratorium Award, NERC Grant NE/X016374/1, Ralf Gertisser. For sample context, see: https://publications.iodp.org/proceedings/398/398title.html https://doi.org/10.14379/iodp.proc.398.109.2024