Blue light-emitting phosphors having the excitation spectrum range of the medium-long ultraviolet ($280nm{sim}400nm$) have been prepared by solid state reaction method. As a starting material the natural alkaline feldspar powder produced from the domestic mine field in Buyeo, Chungnam-do. The photoluminescence characteristics and crystal structures have been analyzed for the phosphor samples. The powder mixture of the natural alkaline feldspar and the rare-earth oxide was calcined at $800{sim}1000^{circ}C;for;3{sim}4h$ in air. The calcined samples we fully ground at room temperature and then heat-treated in the mild reducing gas atmosphere of $5%H_2-95%N_2$ mixture at $1100{sim}1150^{circ}C;for;3{sim}4h$. The natural alkaline feldspar material consists of the monoclinic orthoclase ($KAlSi_3O_8$) and the triclinic albite ($NaAlSi_3O_8$) phases. At the $0.5wt%Eu_2O_3$ addition the PL spectrum showed the maximum intensity and with further increase of $Eu_2O_3$ the PL intensity decreased. The albite phase disappeared in the $Eu_2O_3$ doped phosphors. The effect of the co-doped activator on the PL characteristics have been also discussed.