Iridium is the second densest of all elements. With a melting temperature of 2446°C (4435°F), it is exceeded only by the refractory group metals.

It exhibits excellent high temperature properties and mechanical strength, being used in certain applications, unprotected, in air at temperatures exceeding 2000°C (3632°F). At these temperatures it also shows outstanding resistance to a variety of salts and oxides. It is unaffected by common mineral acids and aqua regia.

This makes iridium an obvious choice for a whole range of high temperature applications. Its high degree of stiffness and resistance to deformation render its fabrication into complex components difficult. Johnson Matthey has spent many years developing an understanding of the methods of working iridium into component form to overcome such difficulties. This experience has enabled Johnson Matthey to work with complex customer drawings to achieve outstanding results.