Ruthenium is an expensive metal and on average costs $30 per gram. A chemical element with atomic number 44, ruthenium (Ru) is a rare transition metal that is inert to most other chemicals. It is mostly used for wear-resistant electrical contacts and production of thick-film resistors. A polyvalent hard white metal, ruthenium does not tarnish at normal temperatures. It dissolves in fused alkalis. It is the 74th most abundant metal on Earth and commercially obtained as a by-product from nickel and copper mining and processing.