ruthenium

Hard, brittle, silver-white, metallic element, atomic number 44, relative atomic mass 101.07. It is one of the so-called platinum group of metals; it occurs in platinum ores as a free metal and in the natural alloy osmiridium. It is used as a hardener in alloys and as a catalyst; its compounds are used as colouring agents in glass and ceramics.

It was discovered by J A Sniadecki in Vilno, Poland, in 1808, and then rediscovered in 1827 by G W Osann and named after its place of discovery, the Ural Mountains in Ruthenia (now part of Ukraine). Pure ruthenium was isolated in 1845 by K K Klaus.