This is a 'preproof' accepted article for Mineralogical Magazine. This version may be subject to change during the production process. DOI: 10.1180/mgm.2021.63 Oberwolfachite, SrFe 3+ 3 (AsO 4 )(SO 4 )(OH) 6 , a new alunite- supergroup mineral from the Clara mine, Schwarzwald, Germany, and Monterniers mine, Rhône, France NIKITA V. CHUKANOV 1,2* , GERHARD MÖHN 3 , FABRICE DAL BO 4 , NATALIA V. ZUBKOVA 2 , DMITRY A. VARLAMOV 5 , IGOR V. PEKOV 2 , LAURENT JOUFFRET 6 , JEAN-MARC HENOT 7 , PASCAL CHOLLET 8 , YANNICK VESSELY 9 , HENRIK FRIIS 4 , DMITRY A. KSENOFONTOV 2 , ATALI A. AGAKHANOV 10 , SERGEY N. BRITVIN 11 , JOY DESOR 12 , NATALIA N. KOSHLYAKOVA 2 , DMITRY YU. PUSHCHAROVSKY 2 1 Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow region, 142432 Russia 2 Faculty of Geology, Moscow State University, Vorobievy Gory, Moscow, 119991 Russia 3 Dr.-J.-Wittemannstrasse 5, 65527 Niedernhausen, Germany 4 Natural History Museum, University of Oslo, PO Box 1172, Blindern, 0318 Oslo, Norway 5 Institute of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka, Moscow region, 142432 Russia 6 Institut de Chimie de Clermont-Ferrand, CNRS, Université Clermont Auvergne, 63000 Clermont-Ferrand, France 7 Laboratoire Magmas et Volcans, CNRS, Université Clermont Auvergne, 63000 Clermont- Ferrand, France 8 Les Emerins, 03430 Vieure, France 9 Route du champ tout seul 1238, 71600 Hautefond, France 10 Fersman Mineralogical Museum of the Russian Academy of Sciences, Leninsky Prospekt 8-2, Moscow, 119071 Russia 11 Department of Crystallography, St Petersburg State University, Universitetskaya Nab. 7/9, 199034 St Petersburg, Russia 12 Im Langenfeld 4, 61350 Bad Homburg, Germany