Iridium is one of the six platinum-group elements discovered in 1803, possessing exceptional physical and chemical properties including extreme resistance to wear, tarnishing, and chemical attack, and the ability to withstand high temperatures. These properties make iridium indispensable to many industrial applications.

Check out the rest of the Platinum Group Metals (PGMs) here: ‘What Are The Platinum Group Metals (PGMs)? Critical Raw Materials’

Why Is Iridium A Critical Raw Material?

Iridium has emerged as a critical raw material due to its extreme supply concentration, essential applications in emerging technologies, unprecedented price volatility, and complete absence of substitutes for key industrial uses.

Iridium represents a textbook example of a critical material where technological progress depends on stable access to an extremely rare element with no substitutes. The convergence of extreme geological scarcity, 90% supply concentration in one country, irreplaceable applications in emerging technologies (5G, green hydrogen, advanced electronics), unprecedented price volatility (up to 1,000% increases), absence of recycling options, and mounting operational challenges creates unique vulnerabilities. The metal’s inclusion in strategic material assessments by both the United States and European Union reflects recognition that secure access to iridium is essential for technological competitiveness and the green energy transition.

Extreme Geological Scarcity

Iridium is one of the rarest elements on Earth, with the upper continental crust containing only 0.022 parts per billion. For perspective, marine pelagic sediments contain less than 0.2 to 1.2 ppb iridium, while river sediments range from less than 0.03 to 2.69 ppb. In seawater, iridium concentrations are “well below the ppt range,” making it essentially undetectable. This extreme scarcity is reflected in global production of merely 7,000-8,000 kg annually, making it one of the rarest industrially-used metals.

Unprecedented Supply Concentration

The most critical vulnerability is iridium’s extreme geographic concentration. South Africa produces approximately 90% of global supply (6,000-7,000 kg annually), while Russia contributes only 200-400 kg per year, Canada 200-300 kg, and Zimbabwe 600-800 kg. The Bushveld Complex contains 230 metric tons of iridium in the UG2 Chromitite and 51 metric tons in the Merensky Reef, while the Great Dyke in Zimbabwe holds 120 metric tons. This means essentially all of the world’s known iridium resources – approximately 400 metric tons – are located in just two African nations. Making matters worse, iridium occurs exclusively as a minor byproduct of platinum and palladium mining, typically representing less than 3% of total PGM production. Production cannot be independently scaled regardless of demand or price signals. Historical data shows minimal output – only 1.4 metric tons of iridium produced from Zimbabwe’s Great Dyke from 1980-2010.

Critical Technological Applications

Iridium’s criticality is amplified by its irreplaceable role in high-technology applications. The electronics sector accounts for 55% of worldwide iridium demand, with specific uses including semiconductor manufacturing where iridium is specifically used as a crucible material for growing high-quality single crystals, including sapphire crystals for LED production and lithium tantalate crystals essential for 5G smartphone technology. In green hydrogen production, iridium-based catalysts are essential for proton-exchange membrane (PEM) electrolyzers, with the BASF electrolyzer plant commissioned in 2025 with 54-megawatt capacity exemplifying this growing demand. Maritime applications represent another critical use, as the International Maritime Organization’s ballast water treatment requirements, effective by September 2024, mandate systems using iridium-ruthenium oxide-coated electrodes. These applications are not substitutable – no other material can withstand the conditions required for crystal growth or provide the catalytic efficiency needed for water electrolysis.

Extreme Price Volatility

Iridium has experienced the most dramatic price appreciation of any industrial metal. Prices increased from $586.90/oz in 2016 to $5,158.40/oz in 2021 – an astounding 779% increase. The metal reached record highs of $6,400/oz in May 2021, representing a nearly 11-fold increase from 2016 levels. Historical data shows iridium prices reaching peaks of $1,600 (in 2005 dollars) during supply disruptions. Major price spikes have coincided with specific disruptions including the Arab oil embargo in the 1970s, work stoppages at South African mines including the 1986 Impala strike, the dissolution of the Soviet Union in 1991, the 2012 miners’ strike where “striking workers at Marikana Mine were killed during protest,” and refinery outages at Anglo American Platinum in South Africa and flooding at Nornickel’s Russian operations in 2021.

Technical Extraction Challenges

Iridium faces unique recovery challenges that compound its scarcity. During fire assay analysis and extraction processes, “heating the prill at higher temperatures removes any remaining lead impurities and quantitatively burns off the remaining ruthenium, osmium, and iridium.” This means standard PGE extraction methods result in significant iridium losses, making recovery rates lower than the 75-85% achieved for platinum and palladium. Additionally, iridium preferentially partitions from immiscible sulfide liquid into monosulfide solid solution (MSS), along with osmium and ruthenium, unlike platinum and palladium which concentrate in residual copper-rich sulfide liquids, affecting where it’s found in deposits and extraction complexity.

Infrastructure & Operational Vulnerabilities

Mining operations face mounting challenges that threaten future supply. Current mining operations in the Bushveld Complex are reaching extreme depths exceeding 2 km, where virgin rock temperatures of 70°C require sophisticated cooling systems. Companies consider 75°C as the operational limit for mining, which will be reached as operations deepen. The January 2008 power crisis forced all South African mines to shut down for five days, demonstrating how infrastructure vulnerabilities can instantly remove iridium from global supply. Mining companies face additional constraints from “power and water, which are both in short supply in southern Africa.”

Limited Strategic Reserves & Recycling

The vulnerability is exacerbated by minimal buffering capacity. The United States has zero domestic production and maintains only 15 kg in the National Defense Stockpile, despite the Defense Logistics Agency authorizing potential disposal of this strategic reserve. Unlike other precious metals, iridium has no significant above-ground stocks to buffer supply disruptions. While palladium and platinum are extensively recycled from catalytic converters, iridium’s dispersion in electronic devices makes recovery technically challenging and economically marginal.

Strategic Import Dependence

U.S. imports ranged from 875 kg in 2019 to 2,310 kg in 2021, sourced primarily from South Africa (48-51%), Germany (18-20%), and the United Kingdom (17-19%). The United States maintains a net import reliance of about 90% for PGEs, indicating extreme dependence on foreign sources. With consumption at 2,310 kg in 2021 valued at $285 million against global production of only 7,000-8,000 kg, even minor supply disruptions create severe shortages.

Interesting Facts About Iridium

1. Atomic number 77 – Iridium sits in the platinum group of the periodic table, positioned between osmium and platinum, with 77 protons in its nucleus.
2. Densest element after osmium – With a density of 22.56 g/cm³, iridium is the second-densest naturally occurring element, only slightly less dense than osmium at 22.59 g/cm³.
3. Highest melting point of platinum group – Iridium melts at 2,446°C (4,435°F), giving it exceptional high-temperature stability among the platinum group metals.
4. Most corrosion-resistant metal – Iridium resists attack from acids, bases, and even aqua regia at room temperature, making it more chemically inert than gold or platinum.
5. Extraterrestrial abundance marker – The Iridium Layer at the K-T boundary contains 30-130 times normal iridium levels, providing key evidence for the asteroid impact that killed the dinosaurs 66 million years ago.
6. Extreme hardness – With a Vickers hardness of 1760 MPa, iridium is much harder than platinum (549 MPa) and gold (216 MPa), though it becomes more workable when heated.
7. Nine oxidation states – Iridium can exist in oxidation states from -3 to +6, with +3 and +4 being most common, giving it remarkable chemical versatility.
8. Natural isotope composition – Iridium has two stable isotopes: Ir-191 (37.3%) and Ir-193 (62.7%), both of which have nuclear spin properties useful in spectroscopy.
9. Discovered through residue – Smithson Tennant discovered iridium in 1803 in the black residue left after dissolving platinum ore in aqua regia, alongside osmium.
10. Superconductivity in compounds – While pure iridium isn’t superconducting, certain iridium compounds like CeIr₃ become superconductors at low temperatures.
11. Gamma-ray source – Iridium-192, a radioactive isotope with a 73.8-day half-life, is widely used in industrial radiography for non-destructive testing.
12. Spark plug electrodes – Iridium’s high melting point and erosion resistance make it ideal for long-life spark plugs that can last over 100,000 miles.
13. Catalyst for hydrogen economy – Iridium complexes are among the most efficient catalysts for water splitting, crucial for hydrogen fuel production.
14. Space-rated crucibles – The Voyager spacecraft carried iridium containers for their radioisotope thermoelectric generators due to the metal’s extreme temperature resistance.
15. Optical properties – Iridium has high reflectivity in the infrared spectrum, making it valuable for specialized mirrors in scientific instruments.
16. Biological inertness – Iridium’s chemical stability makes it biocompatible for medical implants, including certain pacemaker electrodes and neurostimulation devices.
17. Crystal structure – Iridium crystallizes in a face-centered cubic structure with a lattice parameter of 3.839 Å, contributing to its mechanical properties.
18. Fountain pen nibs – The hardness and corrosion resistance of iridium (often alloyed with osmium) makes it perfect for fountain pen tips that maintain their shape over decades.
19. Magnetic properties – Pure iridium is paramagnetic with a very low magnetic susceptibility of +25×10⁻⁶ cm³/mol, making it useful where magnetic interference must be minimized.
20. Rarest stable element – With an average crustal abundance of only 0.001 parts per million, iridium is one of the rarest stable elements on Earth, rarer than gold or platinum.

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