Praseodymium is a chemical element with symbol Pr and atomic number 59. It is also a soft silvery malleable rare earth metal. Praseodymium reacts slowly with oxygen forming a green oxide coating. To protect praseodymium for this reaction, praseodymium is usually stored in a sealed plastic container or covered with oil. Praseodymium also reacts quickly with hot water to form praseodymium hydroxide. Praseodymium, combined with neodymium, is used to create high-power magnets due to its strength and durability. When alloyed with magnesium, praseodymium creates a high strength metal used in aircraft engines. Praseodymium oxide can be used as oxidation catalysts.