Ruthenium is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of its group, ruthenium is inert to most other chemicals. The Baltic German scientist Karl Ernst Claus discovered the element in 1844, and named it after Ruthenia. Ruthenium usually occurs as a minor component of platinum ores; annual production is about 20 tonnes. Most ruthenium produced is used for wear-resistant electrical contacts and the production of thick-film resistors. A minor application of ruthenium is its use in some platinum alloys, and, like many elements located near platinum, is used in automobile catalytic converters.Photograph: Heinrich Pniok