Cleusonite, (Pb,Sr)(U4+,U6+) (Fe2+,Zn)2 (Ti,Fe2+,Fe3+)18 (O,OH)38, is a new member of the crichtonite group. It was found at two occurrences in greenschist facies metamorphosed gneissic series of the Mont Fort and Siviez-Mischabel Nappes in Valais, Switzerland (Cleuson...