Abstract: Scintillation phosphors, infrared and ultraviolet transmitting shaped articles of unrestricted length and arbitrary cross section are formed by multiple extrusion of a relatively small single crystal, melt-grown macrocrystal ingot, or, re-extrusion of a relatively small, fully dense polycrystalline parent mass at a temperature below its melting point and under sufficient pressure to form a fully dense, homogeneous polycrystalline mass. A re-extrudate of a first extrudate is wider in cross section than the parent single crystal, or the first extrudate, yet the scintillation, infrared and ultraviolet transmission properties of the polycrystalline re-extrudate are essentially the same or better than those of the parent single crystal or polycrystalline first extrudate.A polycrystalline re-extrudate is disclosed which is optically the same as, but structurally different from a single crystal or first extrudate. It is both optically and structurally different from a hot-pressed or extruded powder.