Discovery of praseodymium

The date given marks the 1841 discovery by Carl Gustaf Mosander of didymium, a substance that he believed to be a single new element, extracted from compounds of cerium and lanthanum. In 1885 the Austrian chemist Carl Auer von Welsbach showed that didymium was in fact a mixture of two elements. One gave green salts and he named it praseodymium, from the Greek prasios, meaning leek-green, and didymos, meaning twin, and the other he called neodymium. Praseodymium is a soft, silvery metal of the rare earth group which develops a green oxide layer in air. Its compounds are used to tint glass and ceramics yellow and green, in welding goggles, which absorb the glare from heated glass, and in magnets and alloys for aircraft engines.

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