I have compiled a list of sources for the elements that are available to the amateur chemist. Praseodymium will be discussed here.
Praseodymium is one of the more reactive rare earth metals. It forms a trivalent state, like all other lanthanides, that is light yellow-green. Outside of aqueous solution, praseodymium forms some higher oxidation state compounds like the oxide.
In element form: Mischmetal contains a small amount of praseodymium. Carbon arc lamps used in film photography contain praseodymium at their cores.
In compound form: Some yellow colored glass is colored using praseodymium(III) oxide.
Here is my sample of praseodymium. It is a piece of mischmetal.