Rockfall trajectories are mainly influenced by ground contacts, which cause deceleration and changes in the rocks' rotation. The duration of contacts, resulting deceleration and rotational changes are highly variable and generally unknown. Appropriate data are important for improving our understanding of the rockfall process. So we placed three-axis gyroscopes and accelerometers in various rocks and concrete blocks to measure such values. For the first time, we succeeded in recording high-quality data with our newly developed sensors. The measurements detail the path of deceleration while simultaneously recording rotational changes. During contacts with the ground, 400-500 deceleration and rotation values per second are recorded. Very brief ground contacts range between 8 and 15 milliseconds (ms); longer contacts last between 50 and 70 ms.