1. Institute of Geosciences and Geography, Mineralogy/Geochemistry, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany
2. Engineering Department, “Roma TRE” University, Via della Vasca Navale 79, Rome 00146, Italy
3. Nanomechanics Inc./KLA-Tencor, 105 Meco Lane, Oak Ridge, Tennessee 37830, USA
4. Department of Geological Sciences and Center for International Security and Cooperation, Stanford University, Stanford, California 94305, USA