Swedenborgite in calcite

You can hardly distinguish between calcite and swedenborgite in white light. In SW-UV they couldn't be more different. Micheal Gaft, H. Yeates and Lev Nagli suggested that the presence of trivalent antimony may be the cause of the blue luminescence in a paper "Laser-induced time-resolved luminescence of natural margarosanite Pb(Ca,Mn)2Si3O9, swedenborgiteNaBe4SbO7 and walstromite BaCa2Si3O9", European Journal of Mineralogy 2013.
 
 Locality: Langban, Sweden

Source: Fluorescent Minerals Workgroup MKA