where does it all come from?

A friend of a friend told me that most helium is separated from petroleum products. It can be isolated from the atmosphere too, but the petroleum process is more plentiful and cost effective.

At the time it seemed to me that helium would promptly race to the surface and dissipate, probably even find a way to escape the Earth's atmosphere, in just a few million years after the Earth condensed. How would any of it still be hanging around, even deep in pockets of the Earth's crust?

A bit of nuclear physics we are learning this week. The mineral-helium question bubbled back up to the surface, pun intended.

As radionuclides decay, one of the decay products is the alpha particle. When it gets the chance, it rips two electrons from any other atoms nearby---it needs to slow down first, of course, because it is ejected from the decaying atom's nucleus--and in so doing it becomes the noble gas helium.

So geologist types: is most or all of the helium available now created from alpha particles emitted by other decayed mineral nuclides, and how much new helium is being created there? Or is it mostly residual helium created in the last nova that gave us the heavier elements, which we are drawing from a finite supply?

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