Dear all, It is with great sadness that we share the news about Klaus Langer with you: he passed away on 14th of September 2025 at the age of 89 in his adopted country in North Germany, where part of his family lives. Klaus Langer was an international recognized geoscientist, who has published more than 130 articles in international journals, and with an enormous list of international co-operations. He started his scientific career in Kiel in the Chemistry department and after short stations at the universities of Bochum and Bonn he became full professor of Mineralogy at the Technische Universität Berlin in 1978. His main research was in the field of high-pressure synthesis and stability of rock-forming silicate minerals, especially transition-ion bearing minerals under controlled oxygen fugacity, and in the field of electronic absorption spectroscopy of synthetic materials and minerals. In 1985 he became Fellow of the American Mineralogical Society. Klaus Langer played a prominent role in the West-East scientific co-operation, mostly with Ukraine, but also with Russia. He started this co-operation in 1978 - which was a very difficult time for West-East co-operations during the Cold War. From 1989 to 2003 Klaus Langer continuously applied for financial support for research stays of his colleagues from Ukraine and Russia at the Technische Universität, Berlin (West Berlin at that time). Through this continuity he not only changed their scientific and private life, he also made the enormous research results of the eastern groups available for the western world. In recognition of his efforts, he was elected Foreign Full Member of the Russian Mineralogical Society associated to the Russian Academy of Science in 2000, and in 2001 he became an Honorable member of the Ukrainian Mineralogical Society. Monika Koch-Müller, GFZ, Helmholtz Centre for Geoscience Gerhard Franz, TU Berlin Prof. Dr. Monika Koch-Müller Section 4.2 Geomechanics and Scientific Drilling Tel+49(0) 331-6264-1492 +49(0) 176-21544992 e-mail: mkoch@gfz.de; mokomue@yahoo.de ________________________________________ GFZ Helmholtz Centre for Geosciences Telegrafenberg, D-14473 Potsdam Germany https://www.gfz-potsdam.de/en/sec42