Tennant discovered iridium in 1804 in the residue obtained on attacking impure platinum with aqua regia. Its name is derived from the Greek ιρις (rainbow) and reflects the various colours of its salts.


  • One of the platinum-group metals.
  • Like platinum, it is a white metal, though with a glint of yellow.
  • Very hard and brittle.
  • Its volumic mass (22,420 kg/m3) is only slightly less than that of osmium (22,570 kg/m3).
  • Iridium has catalytic properties which enable its use in hydrogenation.


  • In the automotive industry, iridium is used mainly as a component of exhausts for direct injection (GDI) engines and, to a lesser extent, in spark plugs. In the form of alloys with ruthenium, the metal is used in the manufacture of electrodes for the production of chlorine by electrolysis.
  • Iridium has also been used since 1995 as a catalyst in the production of acetic acid. 
  • Iridium linings and fabrications are also used in glass production because the metal is inert in contact with molten glass
  • Other applications include crucibles used to grow synthetic single crystals for LED and data-storage technologies.
  • Iridium also serves as an alloying element to harden the platinum used in pacemakers, medical probes and other applications of this type.
  • The 90% Pt–10 Ir alloy has an extremely low thermal expansion coefficient. It was selected to make the standard metre kept at the “Pavillon de Sèvres” in France.


Recycling accounts for a small proportion of the metal produced globally each year.


      Umicore uses certain monitoring and tracking technologies such as cookies. These technologies are used in order to maintain, provide and improve our services on an ongoing basis, and in order to provide our web visitors with a better experience.

      By clicking on the "Accept all" button you agree to the use of these cookies while using the website. For further information regarding how we use cookies and other tracking technologies, please see section 11 of our website privacy notice

          Necessary cookies are essential and help you navigate our website. This helps to support security and basic functionality and are necessary for the proper operation of our website, so if you block these cookies we cannot guarantee your use or the security during your visit.

          Cookies that help us to understand the behaviour of users of our website. This allows us to continuously improve our website to provide the best information in support of our project aims. These cookies also help us understand the effectiveness of our website. For instance these cookies tell us which pages visitors go to most often and if they get error messages from web pages.

          Cookies that deliver content to you based on your interests, which are assumed from your browsing history. Most Targeting Cookies track users via their IP address and, thus, may collect some Personal Data. Personal Data collected by Targeting Cookies may be shared with third parties, such as advertisers.