Rhodium in the U.S. is primarily found as a byproduct in platinum-group metal (PGM) deposits, notably the high-grade Stillwater Igneous Complex in Montana, where Sibanye-Stillwater mines it alongside platinum and palladium. Other potential U.S. sources include volcanic rocks in Alaska's Gravina-Nutzotin belt, and general deposits in copper-nickel ores, but Montana remains the key U.S. mining area, supplemented by recycling from catalytic converters.
New Age Metals Further Demonstrates Presence of Rhodium at the River Valley Palladium Project near Sudbury, Ontario.
The largest rhodium deposits are scattered across the globe, most commonly found in South Africa, Russia, and North America. South Africa is the dominant producer, accounting for nearly 80% of global rhodium output.
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.
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 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.
While rhodium is extremely valuable (often the most expensive precious metal), Californium is significantly more expensive, costing hundreds of millions per ounce due to its rarity and use in nuclear technology, with Iridium and sometimes other rare elements like Osmium also topping its price, though prices fluctuate.
The most common uses for rhodium include automotive catalytic converters, chemical catalysts, electrical contacts, reflective coatings, and for plating white gold, silver, and other jewelry.
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.
Canada produced 60 minerals and metals at almost 200 mines and 6,500 sand, gravel and stone quarries. The value of Canada's mineral production reached $71.9 billion in 2023. Gold was the top-ranked commodity by value of production in Canada in 2023 with a value of $14.4 billion.
In particular, there is a high demand around the world for platinum, palladium, and rhodium—rare precious metals found inside the catalytic converters. Their job is to help ensure that the unburned residues of carbon monoxide, hydrocarbons, or nitrogen oxides are oxidized and neutralized.
South Africa accounts for approximately 80% of the world's platinum supplies, and its palladium production represents about 40% of the world's gross production. PGM is concentrated in South Africa's 2 billion-year old Bushveld Igneous Complex, especially in complexes found in the Limpopo and North West provinces.
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.
Typically, the amount of rhodium in a catalytic converter is anywhere between 1-2 grams, while the amount of platinum ranges anywhere from 3 to 7 grams and the amount of palladium ranges anywhere from 2 to 7 grams.
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.
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.
Impact of Rhodium on human health
Most people do not come into contact with rhodium, which is highly toxic and carcinogenic. Rhodium compounds "stain" the skin very strongly. The body can absorb rhodium through inhalation. The health effects of exposure to rhodium have not been thoroughly investigated.
Noble metals refer to ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), and gold (Ag).
Rhodium Coated First Surface Mirrors provide high reflectivity and are ideal for orthodontic applications, especially in intra-oral photography. These mirrors feature a rhodium coating, which is an element notably resistant to corrosion and aggressive chemicals and passes severe abrasion tests as per MIL-C-675C.
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.
The “common knowledge” about rhodium is that it is most commonly found in automobile catalytic converters.