These are so-called relaxation datasets for the rate of structural relaxation of glass exposed to high temperatures. The glass is in the form of chips collected during the IDDP-1 drilling project at Krafla Iceland (more below). The chips were generated during drilling in 2011. However, the analysis presented here was developed in 2023 ahead of the ultimate publication in 2024. The data were collected using differential scanning calorimetry, which is a standard method in glass science for measuring the enthalpy of glass relaxation as it is returned to the high temperatures from which it formed. The relaxation rate of the glass from IDDP-1 tells us directly what the rate was at which it cooled. That "cooling rate" in turn allows us to understand what the time available for fragmentation and sintering in geothermal systems is, which has informed this wider project.