Dark gray metal m.p. 1663 ºC; 3025 ºF b.p. 3395 ºC; 6143 ºF density 9.840 g/cc (25 ºC); 614.291 pound/cubic foot (77 ºF)	memory peg
	1907 Georges Urbain, France / Carl Auer von Welsbach, Austria
	Lutetia Parisorum = Paris (Latin)

<Draft version>
The story of discovery and naming of this element began with Carl Gustav Mosander splitting old yttria into three new elements, yttria proper, erbia, and terbia (cf. Yttrium).

In 1860 the Swedish chemist Nils Johan Berlin (1812-1891) denied the existence of Mosander’s erbia, and gave this name to his terbia. In 1878 Marignac split Berlin's terbia in two new earths, terbia proper and ytterbia. Then Marignac's ytterbia, in turn, was split by Nilson in 1879 into scandia and a new ytterbia.

Finally, Nilson's ytterbia was separated by Georges Urbain (1872-1938) in 1907 into neoytterbia and lutecia, with the elements Neoytterbium and Lutecium (note). Urbain named the element after Lutetia Parisorum, the Latin name for Paris:

Auer von Welsbach proposed for these elements the names Aldebaranium and Cassiopeium. (The variant name Celtium, found in some sources, is an error, cf. Hafnium). In the report of the International Commission on Atomic Weights of 1906 it was mentioned that Urbain and Auer had independently proved that the old Ytterbium was a mixture of two elements, for one of which Urbain had suggested, and the Commission approved, the name Lutecium. In 1949 the official IUPAC spelling was altered in Lutetium (note).

Further reading:

• Robert Plohn, "Seltene Erden". Zeitschrift 'Die Koralle', Sept. 1929 (on-line).
• Mary Elvira Weeks, Discovery of the Elements, comp. rev. by Heny M. Leicester (Easton, Pa.: Journal of Chemical Education, 1968), pp. 667-699.
• Seltene Erden. Gmelins Handbuch der anorganische Chemie, 8. Aufl.; System-Nummer 39 (1938).