What is Rhodium?
Rhodium is a rare chemical element closely related to the platinum group. It is considered a transition metal with usually silvery white color. Rhodium that occur naturally are said to contain only one isotope. Due to its rarity as a precious metal, rhodium is considered the most expensive in its class.
Rhodium is a precious metal that is also non-reactive similar to gold. The use of sulfuric acid is the only way to dissolve this particular metal. Since rhodium is inert against corrosion, it is commonly mixed or “alloyed” with other metals like platinum and palladium. Other than its rarity, rhodium is highly-priced and sought after because of its very high reflectance quality – a quality that is almost unique when talking about metals. Because it is silvery-white in color, it is also commonly used in making jewelry, particularly as an alternative to silver. It can also be used as plating for white gold and sterling silver to make the jewelry more flashy and shiny and to resist tarnishing.
It was back in 1803 when rhodium was first discovered by William H. Wollaston. Using platinum and/or nickel ores, Wollaston was able to isolate rhodium which he named after “rhodon”, a Latin word that means rose. During that time, rhodium was still not widely used. Rhodium’s first wide application was as corrosion resistant coating. In the 1930’s rhodium was used in electro-plating by silverware manufacturers. Rhodium was a choice that time in making silver flatware as it results to a high-shine product with less polishing needs. It was also not until after World War II that rhodium was widely used in the jewelry industry as plating for white gold, platinum, and silver.
Today, aside from its use in jewelry plating, rhodium is also used in alloying with platinum and palladium for the manufacture of laboratory crucibles, electrodes for aircraft spark plugs, furnace windings, bushings that are commonly used in the making of glass fibers, and thermocouple elements.