Talk:Extinct radionuclide

... [B]eryllium-10 [is] produced by cosmic ray spallation on dust in the upper atmosphere.

I'm not sure this is entirely accurate. What element acts as the parent for this spallation? If it is something between carbon and oxygen, it is possible that some of the spallation actually uses a gas as the parent and not dust. -- B.D.Mills  (T, C) 02:59, 12 May 2008 (UTC)

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So... how do they know about these? They supposedly left behind their daughter elements but surely there needs to be more indication.

No, that is usually enough, because the daughters have different chemistries from their parents. If you see a lot of thallium in a place where there should be more lead and very little thallium, one immediately suspects ²⁰⁵Pb to have been there; if one then analyses the thallium and notices that there is a great deal too much ²⁰⁵Tl (the electron-capture daughter of ²⁰⁵Pb) and very little ²⁰³Tl (the other stable thallium isotope), there really is no other good explanation. That's also how extinct ²⁴⁷Cm was found, because curium and uranium have vastly different chemistries. (Mind you, ²³⁵U might be considered to be "almost" an extinct radionuclide too; it and ⁴⁰K are the two primordials with half-lives in the right time range that they have been severely depleted, but they're not reduced to mere traces yet as ²⁴⁴Pu would have been.) Double sharp (talk) 04:33, 14 May 2017 (UTC)

needs to be more specific

An extinct radionuclide is one that scientists believe was formed by primordial processes, such as stellar nucleogenesis in the supernova(s) that contributed radioisotopes to the early solar system, about 4.6 billion years ago.

Doesn't that also describe stable nuclides? —Tamfang (talk) 04:12, 8 April 2014 (UTC)

No, because a stable nuclide is not a radionuclide. Dirac66 (talk) 18:37, 8 April 2014 (UTC)

Dubious parent-daughter relationships

The table in the article as currently written has some problematic entries for "daughter" products. For example, it lists 150Sm as the daughter of 154Dy, however, the page on dysprosium isotopes lists 150Gd as the primary daughter. 150Gd (also in the table) in turn decays to 146Sm via alpha decay, and only rarely would decay by β⁺β⁺ to 150Sm. There are numerous entries in the table where the daughter could not be the immediate daughter, and the listing of some isotopes as stable implies that the ultimate stable daughter is not being listed. ArkianNWM (talk) 17:18, 12 January 2018 (UTC)

“The Solar System and Earth formed from primordial nuclides and extinct nuclides”

The phrase is confusing and hinders understanding what does “extinct” mean. First of all, the property of being extinct is local: ²⁶
Al
is extinct on Earth and Venus, but not in the Solar System in general. Secondly, the Solar System and Earth formed from various nuclides. Can anybody bet that supernova debris which contributed to our atomic matter didn’t contain any ¹⁴
C
, for example? Stable or long-lived nuclides are primordial. Non-primordial nuclides have various subsets such as extinct or cosmogenic, and it’s always important to specify where is certain nuclide extinct.

As a related (although distinct) quibble, several listed nuclides are produced on Earth in spontaneous fission, some naturally from uranium isotopes, and hence technically are not extinct. Incnis Mrsi (talk) 07:39, 30 August 2019 (UTC)

I suppose it can be clarified, but all uses of the term extinct seem to refer to Earth. The exact definition or set of extinct, however, is consistent, for several lists or descriptions of extinct radionuclides (e.g. [1], [2]) include any extinct radionuclides whose presence in the early Solar System has been established, even if some of them still are generated through fission or cosmic ray spallation. As that occurrence is established in other sources, it might be possible to split the list into two categories: those that are completely extinct on Earth (e.g. ⁹²Nb, ²⁴⁷Cm) and those produced in minuscule quantities through other rare processes (e.g. ⁴¹Ca, ¹³⁵Cs).

There are also many more nuclides that surely were produced in supernovae (e.g. ⁴⁹V; [3]), but their initial abundance was likely so low that they never occurred in significant quantities on Earth and have since been depleted. ComplexRational (talk) 18:00, 30 August 2019 (UTC)

The principal failure of the phrase is a misleading suggestion that the property to be [now] extinct, on Earth or elsewhere in particular, has anything to do with Solar System conditions. Again, extinct nuclides form only a subset of non-primordial. Wrt Solar System it’s completely pointless to divorce these nuclides (like ¹⁴C) from those nuclides (like ²⁶Al). Incnis Mrsi (talk) 21:00, 6 September 2019 (UTC)

The list of extinct nuclides

There are 37 nuclides with half-lives between that of ¹⁴⁶Sm and that of ¹³⁷La. Why do only 18 of them appear in the list of extinct nuclides?

Among the remaining ones, ²³⁶U, ⁵³Mn, ^210mBi and ¹⁰Be have half-lives longer than 1 Myr. Other than ^210mBi, the three others are said "still being produced on Earth". But an extinct nuclide is one that "has decayed to virtually zero abundance and is no longer detectable as a primordial nuclide", so they are still extinct considering their abundances, no?

The other 15 remaining nuclides are those having half-lives between that of ²⁶Al and that of ¹³⁷La (not included). None of them is classified as an extinct nuclide in the table. 2A04:CEC0:1011:B1F1:C5E3:F416:5CD7:1B03 (talk) 23:45, 13 November 2023 (UTC)