Klemme, Stephan ; John, Timm ; John, T. ; Wessels, Mathias ; Kusebauch, Christof ; Berndt, Jasper ; Rohrbach, Arno ; Schmid-Beurmann, Peter: Synthesis of trace element bearing single crystals of Chlor-Apatite (Ca5(PO4)3Cl) using the flux growth method