Lutetium ranks among the rare-earths in abundance only above thulium and promethium (and there's none of that anyway!). It official name comes from an ancient name for Paris, Lutecia, but it has had many names, most recently lutecium (only a change in official spelling). It was discovered independently by von Welsbach and Urbain in 1907-08.
The refinement of ion exchange methods and their application to the separation of the rare-earths made the separation of lutetium from ytterbium possible. von Welsbach decided to rename ytterbium aldebaranium and picked cassiopium for element 71. Urbain preferred neoytterbium and lutecium. Urbain's choices eventually were accepted, altho
ugh the prefix was dropped from ytterbium and the spelling of lutecium was eventually changed.
The metal is the hardest and densest of the rare-earths and is the last of the lanthanides.
Stephen R. Marsden (ChemTopics)