* A transition metal: It's located in the d-block of the periodic table, characterized by partially filled d orbitals.

* A platinum group metal (PGM): It's part of a group of six metals that share similar chemical properties and are known for their high density, resistance to corrosion, and high melting points.

* A rare element: It's one of the least abundant elements in the Earth's crust.

* A noble metal: It's relatively unreactive and resistant to corrosion, often used in jewelry and industrial applications.

* A catalyst: It's used as a catalyst in various chemical processes, including the production of gasoline and the removal of pollutants.

So, depending on the context, iridium can be considered an example of any of these things.