Rhodium is a chemical element that is silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. Rhodium was discovered in 1803 by William Hyde Wollaston. It is found in platinum ores and is mostly used as a catalyst. Rhodium is usually alloyed with platinum or palladium and applied in high-temperature and corrosion-resistive coatings. Rhodium detectors are used in nuclear reactors to measure the neutron flux level.