Doped fluorophosphate glasses based on pseudo-binary system: barium metaphosphate Ba(PO 3 ) 2 – usovite MgCaSrBaAl 2 F 14 , are studied by means of fluorescence, induced ESR and optical absorption spectra. Doping the glass, containing 5 and 7mol% Ba(PO 3 ) 2 with TbF 3 and EuF 3 results in drastic changes of color and paramagnetic center numbers correspondingly. Post-irradiation process results in separation of the spectra analyzed into groups in dependence of Tb 3+ ion concentration. The crucial concentration, dividing two concentration ranges is not more than 0.02mol%. It is supposed that the local environment of Tb 3+ ion doped up to concentration mentioned is preferably phosphate. Estimates of Eu 3+ ion concentration that have preferably phosphate groupings in their environment result from concentration dependence of PO42− centers and produce the value of approximately 0.01mol%. Close values of two crucial concentrations is interpreted in terms of doped ion segregation model.