Extinct radionuclide

An extinct radionuclide is a <a href="/facts/Radionuclide/5WpCfbdq">radionuclide</a> that was formed by <a href="/facts/Nucleosynthesis/F9MIeADF">nucleosynthesis</a> before the formation of the Solar System, about 4.6 billion years ago, but has since <a href="/facts/Radioactive_decay/Ya6FVjt4">decayed</a> to virtually zero <a href="/facts/Natural_abundance/dGjaAwc9">abundance</a> and is no longer detectable as a <a href="/facts/Primordial_nuclide/lFAUqHDv">primordial nuclide</a>. Extinct radionuclides were generated by various processes in the early Solar system, and became part of the composition of <a href="/facts/Meteorite/NsmHlBlX">meteorites</a> and <a href="/facts/Protoplanet/syFmx3ku">protoplanets</a>. All widely documented extinct radionuclides have <a href="/facts/Half-lives/kGVH8BAB">half-lives</a> shorter than 100 million years.
Short-lived radioisotopes that are found in nature are continuously generated or replenished by natural processes, such as <a href="/facts/Cosmic_ray/uxCVdTKd">cosmic rays</a> (<a href="/facts/Cosmogenic_nuclide/TlJwc4wV">cosmogenic nuclides</a>), <a href="/facts/Background_radiation/LEBeDkGg">background radiation</a>, or the <a href="/facts/Decay_chain/JvTwPNBn">decay chain</a> or <a href="/facts/Spontaneous_fission/0QuJoVKI">spontaneous fission</a> of other radionuclides.
Short-lived isotopes that are not generated or replenished by natural processes are not found in nature, so they are known as extinct radionuclides. Their former existence is inferred from a superabundance of their stable or nearly stable decay products.
Examples of extinct radionuclides include <a href="/facts/Iodine-129/oJDlGf5H">iodine-129</a> (the first to be noted in 1960, inferred from excess <a href="/facts/Xenon-129/Yz78R52h">xenon-129</a> concentrations in meteorites, in the xenon-iodine dating system), <a href="/facts/Aluminium-26/INwQYapg">aluminium-26</a> (inferred from extra <a href="/facts/Magnesium-26/pv5hSrhW">magnesium-26</a> found in meteorites), and <a href="/facts/Iron-60/GVebbg1n">iron-60</a>.
The Solar System and Earth are formed from <a href="/facts/Primordial_nuclide/lFAUqHDv">primordial nuclides</a> and extinct nuclides. Extinct nuclides have decayed away, but primordial nuclides still exist in their original state (undecayed). There are 251 stable primordial nuclides, and remainders of 35 primordial radionuclides that have very long half-lives.

Extinct radionuclide open-in-new

Extinct radionuclide