Textural data and major element geochemical data for plagioclase crystallisation experiments. Data were collected 2020-2022. The aim of the experiments was to produce plagioclase crystals at a variety of sizes at low to moderate undercooling conditions (~0 < ΔT < 45 °C) and characterise their shapes. Experiments, data acquisition and processing were conducted by Dr Martin Mangler and Eshbal Geifman. This research was funded by a NERC grant to Madeleine Humphreys, Richard Brooker, Fabian Wadsworth and Alex Iveson, and by an ERC Consolidator award to Madeleine Humphreys under the European Union’s Horizon 2020 research and innovation programme (grant agreement 864923). Full details of the data analysis and interpretation can be found in Mangler et al. (2023): Melt diffusion-moderated crystal growth and its effect on euhedral crystal shapes, Journal of Petrology, doi.org/10.1093/petrology/egad054.