Iridium

Overview

Iridium is a very dense, hard platinum-group metal (PGM) discovered by Smithson Tennant in 1803. It is the most corrosion-resistant material known and has a very high melting point, which is why it is used in spark-plug contacts and, alloyed with platinum, was used in the old standard metre bar.¹

Today its main uses are in electrodes for chlorine production and copper-foil manufacture, in crucibles for growing crystals for electronics, in spark plugs, in acetic acid catalysts and, increasingly, in proton exchange membrane (PEM) electrolyzers that make green hydrogen.²³

Iridium is critical because it is geologically extremely rare, cannot be mined on its own and has by far the smallest and least liquid market of the PGMs.²³ The United States lists it as a critical mineral, classed as a by-product of platinum and nickel, and the EU covers it through its "Platinum Group Metals" entry on both the critical and the strategic raw materials lists.⁴⁵

Where it comes from

Iridium is recovered as a by-product of platinum and palladium mining, and its output depends on demand for the PGM basket as a whole. Primary supply is dominated by South Africa; the Norilsk-Talnakh deposits in Russia and mines in Zimbabwe, Canada and the United States contain much lower concentrations, and Europe produces essentially none.²

Refined output has been essentially stable at around 7 t a year since 2019.² Johnson Matthey estimates primary supply at 7.1 t in 2025 and expects the same in 2026.³ Neither source publishes a country breakdown in tonnes, so no production chart is shown here.

What it is used for

Global iridium demand was 7.3 t in 2025. Electrochemical uses were the largest category.³

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• Electrochemical. Iridium-coated electrodes are used for chlorine production, water treatment and the electroplating of copper foil for printed circuit boards and lithium batteries.²³ It is also used in anode catalysts for PEM electrolyzers, its highest-profile growth use. Johnson Matthey expects 2026 to bring the first commercial-scale use in green hydrogen, as large projects in Germany and Portugal near completion.³
• Electronics. Iridium crucibles are used to grow synthetic oxide crystals for electronic applications, because they withstand very high temperatures without contaminating the product. Iridium is also used in OLED display materials and platinum-iridium electrical contacts.²
• Spark plugs. All jet-engine spark plugs and most automotive spark plugs use iridium tips.²
• Chemicals. Iridium catalysts are used in the Cativa process for acetic acid, which displaced the older rhodium-based Monsanto process in major plants.²

Iridium supply and demand have been broadly balanced for years, but in 2020–21 interest in hydrogen led buyers to build stocks beyond their needs. A new wave of strategic buying, especially in China, has since reduced market liquidity. Johnson Matthey forecasts a small deficit of about 0.4 t in 2026, with demand at a three-year high.³

Grades and forms

Refined PGMs are typically more than 99.95% pure and are produced as ingots, grains or sponge.² Most iridium is used as fabricated metal (crucibles, spark-plug tips, contacts) or as compounds for electrode coatings and catalysts.²

Trade and policy

The United States imported about 2,200 kg of iridium in 2025, up from 1,360 kg in 2024; unwrought and semi-manufactured PGMs enter duty free under normal trade relations.⁶ Iridium shares its tariff headings with osmium and ruthenium, and the EU's largest sources of iridium and ruthenium imports are South Africa, the UK and the United States.²

Iridium is one of five platinum-group metals named individually on the final 2025 US List of Critical Minerals, published in November 2025.⁴ The US National Defense Stockpile listed 15 kg of iridium as a potential disposal for fiscal year 2025.⁶

Recycling and substitution

Recycled iridium comes almost entirely from closed-loop systems, in which industrial users keep ownership of the metal. Open-loop recycling is not well developed: a spark plug contains only a few milligrams, and there is no collection system comparable to the one for catalytic converters.²

Substitution is possible in some uses. High costs in 2020–21 led some Chinese crucible makers to switch to platinum for certain crucible formats.³ Electrode users can recoat less often, and ultraviolet light can replace iridium electrodes in some water treatment. In electrolyzers, reducing iridium loadings while keeping performance is a major research focus.² Replacement is harder in spark plugs and OLEDs, where iridium's combination of temperature stability and corrosion resistance is difficult to match or where alternatives need a full redesign.²

Sources

1. Iridium: element information, properties and uses. Royal Society of Chemistry, accessed 2026-10-03. ↩

2. PGM Fact Sheet: Iridium (May 2026). International Platinum Group Metals Association, accessed 2026-10-03. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴

3. PGM Market Report May 2026. Johnson Matthey, accessed 2026-10-03. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

4. Final 2025 List of Critical Minerals (90 FR, 7 November 2025). Federal Register, accessed 2026-10-03. ↩ ↩²

5. EU critical raw materials. European Commission Joint Research Centre (RMIS), accessed 2026-10-03. ↩

6. Mineral Commodity Summaries 2026: Platinum-Group Metals. U.S. Geological Survey, accessed 2026-10-03. ↩ ↩²