Rhenium

Rhenium is a dense, silvery metal and one of the rarest elements in Earth's crust. It was the last element with a stable form to be discovered, found in 1925 by Walter Noddack, Ida Tacke and Otto Berg in Germany and named after the river Rhine. It is recovered as a by-product of refining molybdenum from copper ores.

Rhenium has the second-highest melting point of any metal, after tungsten. Its biggest use is in nickel-based superalloys for jet engine turbine blades, where a few percent of rhenium helps the blades resist slowly deforming at fierce temperatures. Combined with platinum, it forms catalysts that help oil refineries make high-octane gasoline.