Iridium (Ir) is one of the world’s rarest elements and belongs to the group of Platinum Group Metals (PGMs). This silvery-white metal is recognized for its extreme properties, including a high melting point of approximately 2,447 degrees Celsius and being the most corrosion-resistant metal known. Its density is second only to osmium, making it a highly specialized material for demanding applications. Due to its scarcity and unique characteristics, the global supply of iridium is overwhelmingly concentrated in a single geographic location.
The World Leader in Iridium Supply
The country that possesses the vast majority of the world’s iridium is South Africa. This single nation is responsible for producing an estimated 80% or more of the annual global supply of this metal. This dominant position means the international market for iridium is highly sensitive to any economic or operational shifts within South Africa’s mining sector.
While a few other countries contribute minor amounts, the remaining global production is primarily sourced from Russia, with trace amounts coming from regions like Zimbabwe and Canada.
The Source of Iridium
The reason for South Africa’s dominance is purely geological, centering on the immense Bushveld Igneous Complex. This vast, saucer-shaped rock formation holds the world’s largest known reserves of Platinum Group Metals, including platinum, palladium, rhodium, ruthenium, and iridium.
Iridium is not the primary target of mining operations; instead, it is recovered as a byproduct during the complex refining process of the more abundant platinum and nickel ores. This means that the supply of iridium is inelastic, tied directly to the global demand for the other PGMs, particularly platinum.
Iridium is extracted from specific geological layers within the complex, such as the Merensky Reef and the UG2 Reef. The UG2 Reef, in particular, is noted for containing a proportionally higher concentration of iridium compared to other PGM-bearing layers.
Key Industrial Applications
Iridium’s unparalleled resistance to heat and corrosion makes it indispensable for high-tech industrial uses where ordinary metals would fail. Its stability allows it to be fashioned into specialized crucibles, which are high-temperature containers used for growing synthetic single crystals necessary in advanced electronics and optics.
The metal is also a foundational component in the emerging green energy sector, specifically as a catalyst in Polymer Electrolyte Membrane (PEM) electrolyzers. These devices use electricity to split water into hydrogen and oxygen, and iridium is the most effective element to facilitate the oxygen evolution reaction.
Furthermore, iridium is alloyed with other metals for components in extreme environments, such as aerospace turbine blades, specialized automotive spark plugs, and durable electrodes used in the chlor-alkali process for producing chlorine and caustic soda.