Rhodium( Rh )
Wollaston discovered rhodium in 1803-4 in crude platinum ore he presumably obtained from South America. .
The metal is silvery white and at red heat slowly changes in air to the resquioxide. At higher temperatures it converts back to the element. Rhodium has a higher melting point and lower density than platinum. It has a high reflectance and is hard and durable.
TThe following uses of rhodium are gathered from a variety of sources.
Alloying agent to harden platinum and palladium. Such alloys are used for furnace windings, thermocouple elements, bushings for glass fibre production, electrodes for aircraft spark plugs, and laboratory crucibles
Used as an electrical contact material as it has a low electrical resistance, a low and stable contact resistance, and is highly resistant to corrosion
Plated rhodium produced by electroplating or evaporation is exceptionally hard and is used for optical instruments
Used for jewelry
Rhodium is used as part of the catalytic system in car catalytic converters, used to clean up exhaust gases to some extent