Iridium is one of the world's rarest industrial metals. It can withstand extreme heat and corrosive chemicals, making it useful in electronics, chemical manufacturing, and green hydrogen production equipment. But unlike gold or copper, iridium has no dedicated mine. Nearly all new iridium reaches the market as a by-product of mines operated for platinum, palladium, and, in some cases, nickel. That fact, not scarcity alone, explains why iridium supply is so difficult to increase.
Iridium is scarce near the Earth's surface partly because of how the planet formed. As the young Earth separated into layers, iridium tended to dissolve in molten iron and sink toward the core. Only tiny amounts remained in the accessible crust. The concentrations high enough to recover commercially occur mainly alongside other platinum-group metals (PGMs). South Africa's Bushveld Complex is the most important source of PGM-bearing ore; Russia is another significant source. Within those deposits, iridium constitutes a small fraction of the metals recovered. Mines target the much larger quantities of platinum and palladium, then collect iridium during refining.
The precise amount of iridium produced worldwide is difficult to measure. Industry estimates generally put annual primary supply in the single-digit metric tons. For perspective, platinum production is measured in hundreds of tons. A disruption that removes a few hundred kilograms of iridium can therefore be significant.
A PGM mine earns its revenue from a basket of metals. Platinum and palladium usually contribute far more to that basket than iridium does. If their prices fall, a mining company may postpone a project or reduce output even while iridium prices rise. Increasing iridium production also means mining and processing more ore and producing more of the other metals it contains. A company cannot simply select the iridium and leave the platinum and palladium underground. Opening new shafts takes substantial investment and years of work. As a result, the iridium supply responds slowly to demand for iridium. Refining adds another delay. After mining and concentration, smelters and refiners remove base metals and separate the individual PGMs. Iridium's resistance to chemical attack, valuable in a finished product, makes that separation especially challenging. The process can take months before refined metal is ready for industrial use.
Iridium already serves several specialized markets. It is used in durable industrial electrodes, high-temperature equipment for growing certain electronic crystals, spark plugs, and catalysts for producing acetic acid. These uses provide continuing demand even without the energy transition.
Green hydrogen could add substantially to that demand. Proton exchange membrane (PEM) electrolyzers split water into hydrogen and oxygen. They can adjust quickly to electricity supplied by wind and solar power, but their oxygen-producing anodes operate under highly corrosive conditions. Iridium-based catalysts are among the few materials able to function effectively and endure in that environment.
The amount of iridium future electrolyzers will require is uncertain. It depends on how quickly projects are built and whether manufacturers can reduce the quantity used in each unit without shortening its life. Researchers are developing thinner catalyst layers and designs that expose more of the iridium to the reaction. Other electrolyzer types can avoid iridium, although they come with different technical trade-offs.
Because mines cannot readily increase iridium output on demand, recovering it from used products matters greatly. Refiners can reclaim the metal from spent catalysts, electrodes, and manufacturing scrap. Eventually, retired PEM electrolyzers may become an important source as well.
Recycling has limits. Iridium often appears as a thin coating or within a complex component, so collection and separation are essential. Electrolyzers must also operate for years before their metal becomes available to recover. Recycling can reduce the need for newly mined iridium over time, but it cannot immediately supply the first wave of new equipment.
Iridium's future therefore depends on three connected efforts: maintaining production from PGM mines, using less metal in each application, and recovering as much as possible when products reach the end of their lives. It may not have its own iridium mine, but the world increasingly needs to manage every kilogram it produces.
