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For ceramic coloring.
(Gr. prasios, green, and didymos, twin) In 1841 Mosander extracted the rare earth
didymia from lanthana; in 1879, Lecoq de Boisbaudran isolated a new earth, samaria, from
didymia obtained from the mineral samarskite. Six years later, in 1885, von Welsbach
separated didymia into two others, praseodymia and neodymia, which gave salts of different
colors. As with other rare earths, compounds of these elements in solution have
distinctive sharp spectral absorption bands or lines, some of which are only a few
The element occurs along with other rare-earth elements in a variety of minerals.
Monazite and bastnasite are the two principal commercial sources of the rare-earth metals.
It was prepared in relatively pure form in 1931.
Ion-exchange and solvent extraction techniques have led to much easier isolation of the
rare earths and the cost has dropped greatly in the past few years. Praseodymium can be
prepared by several methods, such as by calcium reduction of the anhydrous chloride of
Misch metal, used in making cigarette lighters, contains about 5% praseodymium metal.
The rare-earth oxides, including Pr2O3 are among the most refractory
substances known. Along with other rare earths, it is widely used as a core material for
carbon arcs used by the motion picture industry for studio lighting and projection. Salts
of praseodymium are used to color glasses and enamels; when mixed with certain other
materials, praseodymium produces an intense and unusually clean yellow color in glass.
Didymium glass, of which praseodymium is a component, is a colorant for welders goggles.
Praseodymium is soft, silvery, malleable, and ductile. It is somewhat more resistant to
corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a
green oxide coating that spalls off when exposed to air. As with other rare-earth metals,
it should be kept under a light mineral oil or sealed in plastic.
The metal (99%+ pure) is priced at about $70/oz.
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.
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