This element was discovered independently by G. Urbain in Paris in 1907 and by von Welsbach. The name comes from the Latin name for Paris (Lutetia).

Ionization energies
LuI 5.4 eV, LuII 13.9 eV, LuIII 21.0 eV.

Absorption lines of LuII
The equivalent width of LuII 3397(4) in the sun is 0.028.

Behavior in non-normal stars
The element is present in some Ap stars of the Cr-Eu-Sr subgroup (see for instance Jaschek and Brandi (1972)), in the form of LuI and LuII. Poli et al. (1987) found LuI in another Ap star.

Lu occurs in the form of two stable isotopes, Lu175 and Lu176, which are present in the solar system with 97% and 3% respectively of all Lu. There exist 20 unstable isotopes and isomers. Lu176 has a half life of 3.7 × 1010 years and can be used for radioactive dating.

Lu175 can be produced by the r or the s process, whereas Lu176 is a pure s process product.

Published in "The Behavior of Chemical Elements in Stars", Carlos Jaschek and Mercedes Jaschek, 1995, Cambridge University Press.