Praseodymium, atomic no. 59, symbol Pr, weight at 140.91, resembles the typical trivalent rare earths, however, it will exhibit a +4 state when stabilized in a zirconia host. The element is found in most all light rare earth derivatives.
It is highly valued for ceramics as a bright yellow pigment in praseodymium doped zirconia because of its optimum reflectance at 560 nm.
Much research is being done on its optical properties for use in amplification of telecommunication systems, including as a doping agent in fluoride fibers.
It is also used in the scintillator for medical CAT scans.