Recently there are appeared a paper showing how Physics - Iron–Helium Compounds Form Under Pressure. which suggests that there might be helium from the original nebula from which the Sun and solar system formed still locked up in the Earth’s core.

This association of helium with iron might be connected with this item from Minnesota: UPDATE | High helium concentration buried deep in Iron Range - YouTube which opens the prospect of the USA being less dependent on other countries for its supply of helium, which is most often encountered in toy balloons but is essential in its liquid form for many of the body scanners use in medicine.

The helium found in nature is almost entirely as the isotope helium-4, but there is a small amount of helium-3 which is of interest in regard to employment in fusion reactors, and is of great theoretical interest also:

Helium-3 Reveals Matter Abundance in Early Universe

Ancient helium leaking from core offers clues of Earth's formation

A theory to explain why helium-3 is leaking from Earth's core1

The Cosmological Lithium Problem

The next element up, namely lithium, has proved a great headache for cosmologists.  When examining the oldest stars, which formed before supernovae filled the universe with carbon and heavier elements, observations reveal proportions of hydrogen and helium consistent with the models of Big Bang nucleosynthesis, but lithium levels are several times lower than predicted.  It has, among other things, had YouTube being flooded with videos with titles like “Lithium proves the Big Bang wrong”.  I feel that it is far too early to jump to such conclusions.  This Wikipedia article gives a nice summary of the situation.

Cosmological lithium problem - Wikipedia

From Helium to Lithium via Beryllium.

In 2024 there appeared a paper 

Novae: An Important Source of Lithium in the Galaxy - Gao_2024_ApJ_971_4.pdf

with calculations which suggest that the when a nova explosion occurs on the surface of a white dwarf which is accreting material from a red giant companion, the reaction helium-3 + helium-4 produces beryllium-7 which decays to lithium-7 in sufficient quantity to produce a sizable proportion of the Li-7 found in the Galaxy.

Astronomers are eagerly watching the star T Coronae Borealis (Wikipedia), which has been observed to go nova about once every 80 years.  I am looking for it in my search engine with a time limit of last day or week only.

From Helium to Carbon

Among the even numbered elements from helium to to calcium, the most abundant isotope in nature has equal numbers of protons and neutrons in the nucleus.  There are two exceptions, one being argon (Britannica), atomic number 18, with stable isotopes 36, 38, and 40.   Argon-40 comprises 99.6% of the argon found in the Earth’s atmosphere, which has arisen from the decay of Potassium-40, half-life 1.25 billion years.  This is used in geology for potassium-argon dating.

An even more significant exception is beryllium, in which, according to Britannica:

The only naturally occurring isotope is the stable beryllium-9, although 11 other synthetic isotopes are known. Their half-lives range from 1.5 million years (for beryllium-10, which undergoes beta decay) to 6.7 × 10−17 second for beryllium-8 (which decays by two-proton emission). The decay of beryllium-7 (53.2-day half-life) in the Sun is the source of observed solar neutrinos.

 (The decay of Be-7 would account for the higher than expected ratio of Li-7 to Li-6)

But this very short half-life of Be-8 was proving a major headache for astrophysicists, since how could this allow the synthesis of carbon in stars?  The astronomer Fred Hoyle predicted that there must be a energy level in the carbon-12 nucleus very close to one in that of beryllium 8, forming a resonance which would allow 3 helium-4 nuclei to come together to form the carbon-12 nucleus in that short time.  This level in carbon was experimentally shown at Caltech a year later.

This 8-minute video shows the history of this development in understanding, and features the contribution of top nuclei physicists over the years to this understanding.  I highly recommend it.

Which leaves one question, where do the beryllium-9 and boron-10 and 11 found in nature come from?  These must have arisen from the impact of cosmic rays (typically high energy protons) with the nuclei of carbon and possibly oxygen or even higher elements in interstellar space, smashing off one or more nucleons to reduce their atomic number, a process known as spallation.