Symbol Lu. A silvery metallic element belonging to the lanthanoids; a.n. 71; r.a.m. 174.97; r.d. 9.8404 (20°C); m.p. 1663°C; b.p. 3402°C. Lutetium is the least abundant of the elements and the little quantities that are available have been obtained by processing other metals. There are two natural isotopes, lutetium–175 (stable) and lutetium–176 (half-life 2.2×10 10 years). The element is used as a catalyst. It was first identified by Gerges Urbain (1872–1938) in 1907.
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