Rhodium (Rh)
Rhodium (Rh)
Discovered between 1803 and 1804, rhodium occurs naturally with other platinum metals.
It is silvery white, slowly changes to the sesquioxide when heated in air, and converts back to the element at higher temperatures. It is highly reflective, hard, and durable.
Rhodium is used primarily in alloys to harden platinum and palladium, which are then used for furnaces, thermocouple elements, bushings, aircraft spark plugs, and laboratory crucibles. It is corrosion-resistant and its low electrical resistance makes it a good electrical contact material. Rhodium is also used as a catalyst, in optical instruments, and for jewelry and decoration.