In order to study americium incorporation into calcite, CaCO3, under conditions of crystal growth, two samples of single crystal Am-doped calcite were synthesized and studied by cathodoluminescence (CL) spectroscopy in comparison with undoped and Eu-doped artificial calcite. Americium contents in calcite crystals were (in kBq/g): 1) 6.9; 2) 1.9(E+4). The CL emission of undoped and Am-Eu-doped calcitesamples was characterized by three broad bands at 2.03; 2.47 and 2.96 eV. Weak CL lines related to typical transitions 5D0
7F1,2,4 of Eu3+ and Am3+ions were observed at 1.68; 1.99, 2.06 eV and 1.60; 1.98 eV, respectively. Degrading of calcite structure under irradiation has been studied using CL emission of high power electron beam.