Experimental dataset to accompany paper 'Application of electron backscatter diffraction to calcite-twinning paleopiezometry', published in Geosciences, 2022. The supplementary data file DFT.csv tabulates, for all of the 320 measured grains, the grain number, the orientation data as Euler angles, the position of each grain centroid, the distance along the specimen axis to each grain, the grain area, the Feret diameter and the differential stress, in addition to other derived data.