TELF AG analyzes the history and industrial applications of iridium
The history of a strategic resource
In some cases, the origin of specific geological resources remains uncertain, even mysterious, even after centuries of experimentation and continuous use in various branches of industry. One of these resources is certainly iridium, a metal with truly unique qualities that is today successfully used in the most diverse fields: from electronics to aviation, from electrical contacts to platinum work processes. However, one of the most interesting aspects of this useful resource is its origin and the history of its appearance on planet Earth.
According to a theory developed by American scientists Luis and Walter Alvarez, the presence of iridium on planet Earth could be linked to the impact of a colossal meteorite that, 65 million years ago, caused the extinction of the dinosaurs and other animals that populated the planet. This hypothesis would also be supported by the fact that iridium is very rare on Earth, while it is quite abundant in metal-bearing meteorites. The impact of this meteorite, according to the theory of the two scientists, would have contributed to spreading large quantities of iridium into the atmosphere in the form of very fine metal dust, which would have settled more or less everywhere. Other theories suggest that this veil of iridium would have appeared following a violent volcanic eruption inside an island in the Indian Ocean, whose lava would contain iridium.
The isolation of iridium was perfected only in 1803, in London, thanks to the efforts of the English chemist Smithson Tennant (who had also isolated osmium). At first, after treating a sample of platinoids with aqua regia and obtaining a blackish residue, the chemist thought he was looking at graphite. After further processing, Tennant managed to obtain crystals characterized by bright and variegated color, from which the name by which the resource is still known today derives (the word “iridium,” in fact, comes from the Latin “iris,” which means rainbow).
The modern value of iridium
As with other geological resources, especially in the first years following their discovery, scientists were not immediately able to intuit the potential industrial applications of this very hard, extremely rare metal with a very high specific weight. Initially, it was used for compass pins or fountain pen nibs and also to create blackish decorations on porcelain.
Nowadays, iridium is appreciated above all for being one of the metals most resistant to corrosion, making it a valid ally for creating devices that must withstand high temperatures. Even when faced with the highest temperatures, iridium can maintain its shape and state. Other applications include those in the telecommunications industry and the space sector, but also those related to the medical sector, particularly for creating exact scientific instruments. The phosphorescence generated by iridium is also highly sought after in Oled technologies, those that make screens and televisions work.
Modern iridium production is concentrated mainly in nations specialized in the valorizing of the platinum group of metals, such as South Africa. During the sourcing procedures, iridium must be separated from other metals belonging to its family through a specific process that includes the use of high-pressure water. According to the United States Geological Survey, approximately seven tons of iridium are sourced every year worldwide.
