Neutronium (degenerate neutron fluid) is only stable at immense pressure.
Relieve that pressure -- by flinging bits into space in a collision or explosion -- and it reverts to neutrons + protons + electrons + antineutrinos, forming first ultramassive nuclei, which rapidly decay to stable elements, many being heavy elements well above iron in atomic number.
The nuclei mar be formed by r-capture (rapid capture), or perhaps devolve from dense neutronium clumps.
>How is gold created out of the collision of stars composed of neutrons?
They are composed predominantly out of neutrons. Some percentage of their composition is still electrons and assorted atomic nuclei, which is a non-trivial amount of matter considering the common range of density they tend to have.
I would imagine all kinds of interesting(strange?) interactions take place when such dense and energetic objects collide.
That makes a little more sense. The original quote suggests that a single very large lump of gold was created, not a very large number of separate gold atoms.
This raises the question of why gold tends to be found near other gold on Earth.
> This raises the question of why gold tends to be found near other gold on Earth.
When you spin a combination of stuff that is "loose enough" at sufficient speeds, the centrifugal force acts on the constituent masses differently. As a result similar masses coalesce.
This is the same principle used to separate and concentrate (enrich) all kinds of stuff in centrifuges.
Is there an answer to that question? And, why is the distribution of matter not random? Maybe some sort of gravitational grouping? (eg earth's iron core, centrifugal enrichment of uranium).
Or affinity for some orientation relative to field states, magnetism/diamagnetism etc.?
As I understand it, the distribution was decided when the earth was still hot. So the mechanics you're interested in are those of high-temperature solutions containing liquid gold, which I don't understand that much. There's other interesting phenomena too, like gold frequently occurs in quartz rocks[0].
I'm not a geologist at all, but when you freeze soda you tend to get water ice infused with veins of high-sugar soda concentrate. I wouldn't be surprised if similar mechanisms tend to lump matter with similar melting points together in molten rock.
Deep in the earth matter tends to clump together by density, just as oil separates from water due to density. There is still some dynamism though so temporary mixing does occur.
Gold at earth's surface tends to be found in deposits where water with gold particles in it was flowing through a crack for an extended period of time.
Over time some of the gold is deposited on the sides of the crack, essentially concentrating it through evaporation and deposition.
These cracks then become what miners call 'veins'. Other metals and minerals have similar stories.
TLDR: water from deep in the earth carries gold particles upward. Cracks form consistent flows which concentrate deposits over time.
Materials separate by MACROSCOPIC density. However, heavy elements can be chemically bound in light materials. Uranium, for example, is highly concentrated in the Earth's crust compared to the mantle.
Gold is a siderophile element, chemically favoring to bind with iron metal, and preferentially went into the Earth's iron core when the planet differentiated.
This is why mining asteroids for siderophiles (like gold, but also platinum group elements) has been a staple of space advocacy.
Relieve that pressure -- by flinging bits into space in a collision or explosion -- and it reverts to neutrons + protons + electrons + antineutrinos, forming first ultramassive nuclei, which rapidly decay to stable elements, many being heavy elements well above iron in atomic number.
The nuclei mar be formed by r-capture (rapid capture), or perhaps devolve from dense neutronium clumps.
https://www.nature.com/articles/nature04807
https://en.wikipedia.org/wiki/Neutronium