1. Grebenshchikov Institute of Silicate Chemistry, Makarov Emb. 2, St. Petersburg 199034, Russia
2. Department of Crystallography, Saint Petersburg State University, University Emb. 7/9, St. Petersburg 199034, Russia
3. Laboratory of Arctic Mineralogy and Material Sciences, Kola Science Centre, Russian Academy of Sciences, Apatity 184209, Russia