Low-mass stars, like the Sun, will generally expand into many times their original size after hydrogen starts running out in their core. Much of these tenuous outer layers will be emitted during the final stages of the star, before the core collapses into a white dwarf.
Perhaps a simpler way of asking: are the heavy elements we find on earth typical for an average planet? Or does a planetary system have to be "lucky" enough to have formed near a neutron star merger, for it to have elements like gold in measurable quantities?
Thanks - I had managed to miss the fact that being made in a neutron star collision implies that things like gold were once part of neutron stars.
I think this exceeds the coolness of having been in a supernova.
On the other hand, giant stars explode after just a few million years so it didn't take long for other elements to appear.
Nothing specific on what Type II stellar systems and planets would be like, though I'd suspect gas giants, generally.
Crustal deposits of heavier minerals largely result from late bombardment (after the crust had formed, about 100 million years after Earth's formation itself), geothermal and tectonic activity (volcanism, rift zones, vents), and biological mobilisation and concentration (e.g., lighter elements in coal and limestone, but notably, banded iron formations). Events such as the hypothesized Tethys collision could of course also have influenced distribution.
Gold forms veins typically in quartzes through differential precipitation AFAIU.
Ore formation is its own fascinating subfield of geology, and is underappreciated by many advocates of space mining.
https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...
https://en.wikipedia.org/wiki/Planetary_differentiation
Those who would like to know more could do worse than pick up Greenwood's & Earnshaw's book (this one: https://www.amazon.com/-/dp/0750633654) from the nearest university library, it has a chapter on nucleogenesis and cosmic and geologic abundances.
Cool. Do you have a quick reference for the 'landed' part? As opposed to being part of the planet from the beginning. Thanks!
Is it because all heavy elements present when Earth formed sank to the center?
That would make sense, but I've assumed that since we can mine gold, that's not what happened. If all the gold fell from the sky, that would explain things.