1. Faculty of Mining and Geology, University of Belgrade, Đušina 7, 11000 Belgrade, Serbia
2. Department of Geology, Faculty of Natural Sciences and Engineering, University of Ljubljana, Aškerčeva Cesta 12, 1000 Ljubljana, Slovenia
3. Centre for Electron Microscopy, Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
4. Gaseous Electronics Department, Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia