Did you know that rhodium is currently the most expensive precious metal? At a whopping $10,300 per ounce, it’s definitely not your average metal. But what exactly makes it so valuable?
Well, for starters, rhodium is a noble metal, which means it doesn’t easily react to oxygen. This makes it incredibly resistant to corrosion and oxidation, making it a perfect catalyst. With a melting point of 1,964 degrees Celsius (3,567 degrees Fahrenheit), it’s no wonder that rhodium is part of the prestigious platinum group metals.
But that’s not all. Rhodium can withstand water and air temperatures of up to 600 degrees Celsius (1,112 degrees Fahrenheit) and remains insoluble in most acids. This versatility makes it highly sought after for use in cars, aircraft, electrical contacts, and high-temperature thermocouple and resistance wires.
Now, here’s where it gets really interesting. Rhodium is incredibly rare, occurring at a mind-boggling 0.000037 parts per million in the Earth’s crust. To put that into perspective, gold is found at an abundance of around 0.0013 parts per million. It’s no wonder that rhodium is considered one of the rarest elements on our planet.
Most of the world’s rhodium is produced in South Africa and Russia, mainly as a by-product of refining copper and nickel ores. With an estimated reserve of 3,000 tonnes and an annual production of 16 tonnes, it’s clear that rhodium is a precious commodity.
The discovery of rhodium dates back to 1803 when William Hyde Wollaston, an English chemist, extracted the element from a piece of platinum ore. Interestingly, this discovery came shortly after Wollaston found another platinum group metal, palladium.
While rhodium may appear silver-white in its solid form, its name actually comes from the Greek word “rhodon,” meaning rose. This refers to the red color of the metal’s salts.
Despite its rarity and beauty, the majority of rhodium demand comes from the auto-catalyst sector, specifically in the production of catalytic converters. It’s a somewhat unceremonious use for such a precious metal, but it just goes to show how valuable rhodium truly is.
So, the next time you come across rhodium, remember its incredible rarity and the fascinating story behind it. It’s not just any metal – it’s a true gem.
An earlier version of this article was published in March 2023.
