CONDENSED ALKALI URANYL PHOSPHATE PHOSPHORS COACTIVATED WITH RARE EARTH IONS WHEREIN THE ALKALI METALS ARE CHOSEN FROM THE GROUP LITHIUM, SODIUM, POTASSIUM, RUBID IUM AND CESIUM AND THE RARE EARTH COACTIVATORS ARE CHOSEN FROM THE GROUP EUROPIUM, SAMARIUM AND NEODYMIUM. THESE PHOSPHORS, WHEN EXCITED BY ULTRAVIOLET, ELECTRON, ION OR X-RAY RADIATION, EXHIBIT DOMINANT EMISSION COLORS WHICH MAY BE VARIED FROM GREEN TO RED THROUGH WHITE DEPENDING UPON THE COACTIVATOR SELECTD AND THE MOLAR CONCENTRATIONS. THE PHOSPHORS, MAY BE UTILIZED AS COLOR CORRECTORS FOR MERCURY LAMPS, IN CATHODE RAY TUBE SCREENS INCLUDING SCREENS FOR COLOR TELEVISION TUBES, AND IN DETECTORS FOR ION OR X-RAY BEAMS.