The earth was thought to contain a mixture of elements, and not a fundamental substance in its own right. Spectroscopic data of didymium yielded two absorption bands, one in the blue region and another in the yellow. Praseodymium is a silvery white, fairly soft, malleable, and ductile metal. It is moderately reactive in air, developing a green oxide coating that falls off to expose fresh metal for further oxidation . The metal is also quite reactive in water.
Praseodymium is a rare-earth metal, and is also a member of the lanthanide series .
Praseodymium is used as high-strength alloying agent in the magnesium used in parts of aircraft engines. It is an important alloying agent in steel. Other applications include using a mixture of praseodymium and neodymium in the manufacture of welder's and glassmaker's goggles because they filter out the yellow light in glass blowing. Certain praseodymium compounds are used as yellow pigments.