1. Laboratory of Chemical and Mineralogical Crystallography, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
2. Laboratory of Crystallography, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland
3. Institut für Mineralogie, Am Hubland, 97074 Würzburg, Germany