Cathodoluminescence (CL) investigations of Phanerozoic marine limestones, sinter calcites and saddle dolomites of hydrothermal veins indicate that in contrast to previous knowledge rare earth element (REE)-activated CL in sediments is common. The methods of high-resolution spectrometric analysis of CL emission (HRS-CL) combined with hot-cathode CL microscopy are able to prove qualitatively some REE below the detection limits of electron microprobe and proton-induced X-ray emission analysis (PIXE). Our investigations document Sm 3 + , Dy 3 + , Tb 3 + and probably Ho 3 + -activated CL in calcite and Eu 3 + -activated CL in a saddle dolomite of hydrothermal veins. Sometimes the REE-activated CL is hidden by dominant Mn 2 + emission. In such cases the REE emission spectrum may be obtained by subtracting a spectrum of luminescence produced only by Mn 2 + .The occurrence of only one REE in natural samples is uncommon. In all observed samples REE are present in groups.