Isotopes of iridium

There are two natural isotopes of iridium, ¹⁹¹Ir and ¹⁹³Ir, both stable. In addition, there are 40 known radioisotopes with mass numbers 164 through 205, the most stable being ¹⁹²Ir with a half-life of 73.82 days, and many nuclear isomers, the most stable of which is ^192m2Ir with a half-life of 241 years. All other nuclides have half-lives under two weeks, most under a day. All isotopes of iridium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.
The isotope ¹⁹¹Ir was the first one of any element to be shown to present a Mössbauer effect. This renders it useful for Mössbauer spectroscopy for research in physics, chemistry, biochemistry, metallurgy, and mineralogy.

List of isotopes

Iridium-192 is a radioactive isotope of iridium, with a half-life of 73.82 days. It decays by emitting beta particles and gamma radiation. 95.24% of ¹⁹²Ir decays occur via β^- emission, leading to ¹⁹²Pt; the remaining 4.76% occur via electron capture to ¹⁹²Os; both modes involve gamma emission. Iridium-192 is normally produced by neutron activation of natural-abundance iridium metal.
Iridium-192 is used in brachytherapy and in industrial radiography, particularly for nondestructive testing of welds in steel in the oil and gas industries.