Lutetium

(Lutetia, ancient name for Paris, sometimes called cassiopeium by the Germans) In 1907,Urbain described a process by which Marignac's ytterbium (1879) could be separated intothe two elements, ytterbium (neoytterbium) and lutetium. These elements were identicalwith "aldebaranium" and "cassiopeium," independently discovered atthis time. The spelling of the element was changed from lutecium to lutetium in 1949.Lutetium occurs in very small amounts in nearly all minerals containing yttrium, and ispresent in monazite to the extent of about 0.003%, which is a commercial source. The puremetal has been isolated only in recent years and is one of the most difficult to prepare.It can be prepared by the reduction of anhydrous LuCl3 or LuF3 by an alkali or alkaline earth metal. Themetal is silvery white and relatively stable in air. While new techniques, includingion-exchange reactions, have been developed to separate the various rare-earth elements,lutetium is still the most costly of all rare earths. It is priced at about $75/g. 176Luoccurs naturally (2.6%) with 175Lu (97.4%). It is radioactive with a half-life of about 3x 1010 years. Stablelutetium nuclides, which emit pure beta radiation after thermal neutron activation, can beused as catalysts in cracking, alkylation, hydrogenation, and polymerization. Virtually noother commercial uses have been found yet for lutetium. While lutetium, like otherrare-earth metals, is thought to have a low toxicity rating, it should be handled withcare until more information is available.