Iridium is a transition metal with the symbol Ir and atomic number of 77. It was discovered in 1803 by Smithson Tennant in the residue left after dissolving platinum in acids. Iridium is a solid at room temperature, has the highest melting point of any metal, and is mainly used as a hardening agent in platinum alloys and for equipment requiring high heat resistance. It is found naturally with platinum and osmium and recovered as a byproduct of nickel mining.
3. History of Iridium
Discovered in 1803 by Smithson Tennant
(English; Yorkshire, England)
It was found in the residue left behind by
platinum when it dissolved in a mixture of
hydrochloric acid and nitric acid.
The term Iridium comes from the Latin term
“iris” (rainbow) because many of the salts
found within Iridium were brightly colored.
5. Properties of Ir
Iridium is a solid at room temperature.
Color: white
Boiling point: 4703 K (4430˚C)
Melting point: 2720 K (2447˚C)
Density: 22.56 g/cm³ (at 293 K)
The most common isotope of Iridium is
193Ir and the most stable are 193Ir and 191Ir
6. Uses of Ir
Iridium is mainly used in platinum alloys as
a hardening agent.
It is also used in making crucibles and
making equipment that is used at high
temperatures, heavy-duty electrical
contacts, and in the tips of pens.
Radioactive isotopes are used in cancer
treatment in radiation therapy.
7. Availability of Ir
Iridium is found with platinum and osmium
in alluvial deposits in many alloys
It is also recovered as a by-product in the
nickel mining industry
Cost: $2300 for 100g in bulk