Discovered | Name | Characteristics | Uses

Praseodymium is a metal and a member of the lanthanide or rare earth elements, which stretches from lanthanum (La) through lutetium (Lu).

The isolation of the element was difficult, as was the case for most of the lanthanides. Their chemical similarity means that they are often found in the same mineral deposit and that they behave similarly when one tries to separate them. In 1841 Mosander separated a rare oxide that he called didymia from another mineral lanthana. In 1885 Auer separated didymia into two other oxides, praseodymia and neodymia, which in turn gave salts of different colors. Pure praseodymium metal was not isolated until 1931.

The name of the element comes from the Greek words prasios (green) and didymos (twin).

Pr metal is silvery in appearance and is soft, malleable, and ductile. It should be protected from air as it will form a coating of green Pr2O3.

An alloy of various rare earth elements, misch metal, is about 5% praseodymium. The metal is used for making lighter flints, among other things.

The glass in welding masks contains a mixture of Pr and Nd oxides, because these oxides filter out certain wavelengths of light. Glass may be colored green by Pr2O3, and some photographic filters and ceramic tiles may contain this oxide as well.