1. Nanomaterials Research Centre Kola Science Centre Russian Academy of Sciences Fersmana str. 14 184209 Apatity Russia
2. Department of Crystallography Institute of Earth Sciences University Emb. 7/9 199034 St. Petersburg Russia
3. Dipartimento di Scienze della Terra Università degli Studi di Firenze via La Pira 4 50121 Firenze Italy