In this study, we investigate the effect of the availability of sites for heterogeneous nucleation on the microstructure of moderately to highly undercooled synthetic trachybasalts under anhydrous and hydrous (2 wt% H₂O) conditions. Experiments were performed at 400 MPa by cooling melts from 1300 °C to target temperatures of 1150 °C, 1100 °C, and 1050 °C, followed by isothermal holds of 5 or 30 min. In one experimental series,...

To develop new criteria to distinguish different crystal nucleation mechanisms in silicate melts, we performed crystallization experiments using a synthetic hydrous (2 wt% H 2 O) trachybasalt and combined three-dimensional information from synchrotron X-ray computed microtomography with two-dimensional mapping of crystallographic orientation relationships (CORs) using electron backscatter diffraction. Crystallization experimen...