In 1885, Auer von Welsbach used a method of fractional crystallization that he had developed himself to separate the alloy didymium into its two parts, for the first time.
It had previously been believed to be an element.
 
After 167 crystallizations, Auer von Welsbach differentiated it into two colored salts: he named the green colored salt "praseodymium" and the pink one "neodidymium".

He announced his achievement to the Vienna Academy of Sciences on 18 June 1885.
His achievement was approved by Bunsen, but met with considerable skepticism from others.

The name "neodidymium" is derived from the Greek words neos (νέος), new, and didymos (διδύμος), twin.
The name praseodymium comes from the Greek prasinos (πράσινος), meaning "green".

In naming both elements, and not leaving the original name didymium to the more-abundant component, Auer von Welsbach diverged from established practice, which was to give a new name only to the less-abundant component.
Nonetheless, his name for the major fraction, neodidymium, after some modification, became the name of the element neodymium.
Praseodymium was also accepted as the name of the minor fraction.
In 1885, Auer von Welsbach used a method of fractional crystallization that he had developed himself to separate the alloy didymium into its two parts, for the first time. It had previously been believed to be an element.  
After 167 crystallizations, Auer von Welsbach differentiated it into two colored salts: he named the green colored salt "praseodymium" and the pink one "neodidymium". 
He announced his achievement to the Vienna Academy of Sciences on 18 June 1885. His achievement was approved by Bunsen, but met with considerable skepticism from others.
The name "neodidymium" is derived from the Greek words neos (νέος), new, and didymos (διδύμος), twin. The name praseodymium comes from the Greek prasinos (πράσινος), meaning "green".
In naming both elements, and not leaving the original name didymium to the more-abundant component, Auer von Welsbach diverged from established practice, which was to give a new name only to the less-abundant component. Nonetheless, his name for the major fraction, neodidymium, after some modification, became the name of the element neodymium. Praseodymium was also accepted as the name of the minor fraction.
Carl Auer von Welsbach