Rhodium is a rare metal primarily found within platinum-group metal (PGM) ores, nickel-copper sulfide ores, and in rare cases, in river sediments. It is almost never mined directly, but instead produced as a byproduct of mining these other minerals, often located in complex igneous rocks. Major deposits are found in:
Rhodium is found in platinum or nickel ores with the other members of PGMs.
Rhodium is the rarest of all non-radioactive metals. It occurs uncombined in nature, along with other platinum metals, in river sands in North and South America. It is also found in the copper-nickel sulfide ores of Ontario, Canada.
The “common knowledge” about rhodium is that it is most commonly found in automobile catalytic converters.
Although the underlying metal may be magnetic, the rhodium plating itself is not magnetic. Thus, if you have a piece of jewelry that has been rhodium plated, it will not be magnetic.
Rhodium: Stillwater Complex, Montana, USA
The Stillwater Complex in Montana is a distinct geological formation responsible for some of the world's most notable rhodium discoveries. As the largest known rhodium deposit globally, it holds estimated reserves of over 700,000 ounces.
RHODIUM (METAL FUME) is flammable. Acts as a reducing agent. Reacts violently with BrF5, ClF3 and OF2. Reacts with fluorine, with chlorine (when heated), hydrogen peroxide, sulfur dioxide (when heated), and nitrogen dioxide.
Rhodium is found in platinum or nickel ores with the other members of the platinum group metals. It was discovered in 1803 by William Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds.
The HSEs, in decreasing order of abundance, are platinum, ruthenium, palladium, osmium, iridium, rhodium, gold, and rhenium. Note that all of these elements occur in concentrations of less than 2 ppm (<2000 ppb) in ordinary chondrites (Table). Concentrations are even lower in other types of stony meteorites.
Top 9 rarest precious metals on Earth
Rhodium is used for several different things, such as automobiles, jewelry, searchlights, electronics and mirrors. By far the most common use is in catalytic converters, which are exhaust emission control devices that look like a small muffler on the outside of a vehicle.
The rarest metal on Earth is often considered rhodium, though iridium and osmium are also contenders, all part of the Platinum Group Metals (PGMs); rhodium is incredibly scarce (around 0.000037 ppm in the crust) and valuable, primarily used in catalytic converters, while iridium is valued for extreme hardness and corrosion resistance, and osmium is the densest, making them all extremely rare and expensive.
A typical catalytic converter contains approximately 1–2 grams of rhodium, but this number fluctuates based on vehicle class, design, and age.
Never mix hydrogen peroxide with bleach, ammonia, vinegar, or rubbing alcohol, as this creates toxic fumes (like chloramine or chloroform) or highly corrosive peracetic acid, causing severe irritation or worse. Also avoid mixing it with certain metals (iron, copper, brass) or organic materials due to fire/explosion risks, and always use it in well-ventilated areas with gloves.
Aqua regia has been used for the dissolution of rhodium alloy samples.
While you might imagine that extracting the precious metal content from catalytic converters would be as simple as cracking the converter open and prying the platinum, palladium, or rhodium out, it's actually an incredibly sophisticated process.
Raw rhodium is a sight to behold, characterized by its silvery-white sheen that exudes an almost mirror-like quality. This rare metal, part of the platinum group, stands out not just for its scarcity but also for its striking visual appeal.
Rhodium prices are dropping due to a combination of increased supply (from better mining recovery and recycling) and weakening demand, primarily driven by the shift towards electric vehicles (EVs) which use fewer internal combustion engine (ICE) catalytic converters, plus technological advancements reducing its use in other areas like fiberglass, and significant inventory destocking from major players like Chinese manufacturers. High prices previously incentivized efforts to use less rhodium, leading to a significant price collapse from its peak.
Historically, Rhodium reached an all time high of 29800 in March of 2021.
Platinum, palladium, and rhodium are rarer than gold. Iridium, osmium and ruthenium are even rarer than the other three.