What is Rhodium?

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  • Written By: Michael Anissimov
  • Edited By: Bronwyn Harris
  • Last Modified Date: 16 May 2020
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Rhodium is a silvery-white transition metal that holds the distinction of being the world's most expensive precious metal. It has an atomic number of 45 and is about as nonreactive as gold. The only way to dissolve rhodium is with sulfuric acid. Part of this metal's appeal comes from its high reflectance, almost unique among the metals. It is sometimes used as an expensive and flashy alternative to silver in jewelry, on which it is sometimes plated. Some of the most expensive consumer items in the world are made from rhodium.

This element was discovered in 1803 by William Hyde Wollaston, who isolated it from platinum. He named it after the Greek word rhodon, meaning rose, because of the color of the solution of salts. Wallaston was also the discoverer of palladium.

The price of rhodium is about six times more than gold by weight. It is never found in mineral form, only being found in trace amounts within platinum or nickel ores. 80% of the world's supply comes from South Africa, and world production of the metal is only about 20 tons per year.

Rhodium is a fission product in the decay of the isotope uranium-235, but only about 1% by weight, and most nuclear fuels only contain about 3% uranium-235, meaning only 1% of 3% of nuclear waste consists of this metal. Despite rhodium's great value, the cost of separating it out is generally greater.

There are 25 known isotopes of this metal in all, most with a half-life of less than an hour. This quantity of isotopes is typical among elements with atomic numbers in this range. Rhodium compounds exist, but not outside of the laboratory. They are highly poisonous.

Rhodium was made famous in 1979 when the Guinness Book of World Records awarded Paul McCartney a rhodium-plated disc to celebrate his status as history's all-time best-selling songwriter and recording artist. This metal is used when other precious metals such as silver, gold, or platinum are considered not enough.

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Post 4

I have an old pair of salt and pepper shakers from the quaker silver co. That are marked rhodium plated are they expensive? Thanks alexis

Post 3

I have a bracelet and ring purchased in Athens. The ring is fine, but the bracelet links are cracking and breaking A jeweller said it is Rhodium. Hard to fix. Are there different grades of rhodium? It was a hand made set. No problem with color like Dawn's ring, but want to find out more. --Cass

Post 2

I think the solution you are talking about is when it is being electroplated again. For those that may not know, electroplating is when an object is put into a chemical solution and small particles of another metal are transferred (with the use of electricity) to the other object. This puts a very thin layer of one metal over top of the other to give it the look of the expensive metal. You can do electroplating at home but I really don't think it would be worth it. I think the chemicals are smelly and dangerous and buying a hunk of Rhodium to leech the particles off of would cost way too much (over five grand an ounce these days). My description of the process may not be accurate but you get the idea.

Post 1

I have a ring which needs to be dipped in rhodium solution every so often as the silver like color seems to disappear and the goldish color starts showing through. The ring is 18 carat white gold. Do you know if I can purchase this solution and ask why they would use this chemical on the ring if it wears off?

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