Rhodium

Rhodium is an element with atomic number 45 and the chemical sign Rh. The name comes from the Greek "Rhodon" which means rose.

Rhodium, which is a platinum metal, is the rarest metal on earth (apart from the radioactive metals) and is only a few (less than 10) tons a year are produced.

The metal is silvery white and has a higher melting point and lower density than platinum. Rhodium has low electrical resistance, low and stable contact resistance and high resistance against corrosion.

Rhodium is mainly used in alloys with platinum and palladium.

Rhodium can only be plated on nickel, silver, gold or platinum.

Plated rhodium is extremely hard wearing.

Rhodium is sometimes used in spark plugs for aircraft engines, the tip of fountain pens, telephone relays and in the reflectors of headlamps, mirrors and optical instruments. Rhodium is also used in jewellery, as decorations and as a catalyst.

Because of its low and stable contact resistance and its high resistance against corrosion and wear (for example contact surfaces grinding against each other) it is eminently suitable as material in different kinds of connectors.

A surface plated with gold, which is a very soft metal, is worn off much faster than a surface plated with a hard metal like Rhodium.

Summing up: Gold is beautiful, but if you want the best (in sound as well) use Rhodium.