An Etymological Dictionary of Astronomy and Astrophysics

A hard, silver gray metal belonging to the → platinum group
of metals; symbol: Ru. It is found directly above osmium in Group 8 of the periodic table. → Atomic number 44, → atomic weight 101.07, → melting point about 2,310°C, → boiling point about 3,900°C, → specific gravity 12.41 at 20°C.

See also: From L. ruthenia “Russia,” because it was first found by the Russian chemist Gottfried Wilhelm Osann in 1828, despite not being recognized as an element. In 1844 the Russian chemist Karl Karlovich Klaus was able to isolate the ruthenium metal.