The first observation of a super-hydrated phase of the clay mineral kaolinite could improve our understanding of processes that lead to volcanism and affect earthquakes. In high-pressure and high-temperature X-ray measurements that were partly conducted at DESY, scientists created conditions similar to those in so-called subduction zones where an oceanic plate dives under the continental crust. The transport and release of water during subduction causes strong volcanic activity. An international team led by scientists of Yonsei University in the Republic of Korea, presents the results in the scientific journal Nature Geoscience.