Rhenium

Rhenium is element number 75 and carries the symbol Re due to its being named after the Rhine River which is Renus in latin. A silvery-white, rare, heavy, mulit-valent transition metal, rhenium resembles manganese chemically but tungsten and molybdenum metallurgically. Rhenium is obtained as a by-product of molybdenum conversion to from molybdenite to molybdenum oxide. and rhenium-molybdenum alloys are superconducting. It was the last naturally occurring element to be discovered and belongs to the ten most expensive metals on Earth. The element is used in platinum­rhenium catalysts which are used in making lead-free, high-octane gasoline. It is also used in high-temperature super alloys that are used to make jet engine parts and as an additive to tungsten in some X-ray sources.