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Old 10-21-2017, 09:47 PM
Lucas Jackson Lucas Jackson is offline
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Neutron star collision - gold formation

So as I understand it (very simply put) when two neutron stars collide they create and throw out lots of gold:
https://www.google.com/amp/abcnews.g...-gold-50509163
This gold is in dust form (along with lots of other materials) that gravity may one day draw together as a planet, such as earth.

My question is, why is earth's gold in veins? Why aren't the gold particles just mixed in randomly with all of the other materials that originally formed the earth?
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Old 10-21-2017, 09:57 PM
Chronos Chronos is offline
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I don't know the full answer, but two pieces of it: For one thing, gold is very dense, nearly the densest chemical substance in the Universe ("chemical substance" as opposed to the material of white dwarfs or neutron stars). When the proto-Earth was still molten, the various materials tended to separate out by weight. This naturally put most of the Earth's gold in the core; it's only occasionally that volcanic activity brings some to the surface.

Also, unlike most metals, gold is extremely unreactive. Most metals are found in the form of oxide ores: It's only copper, silver, and gold, plus a few even less common than gold, that are found in their pure form.
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Old 10-21-2017, 10:39 PM
beowulff beowulff is offline
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One current theory is that Gold is dissolved in water, and gets deposited in vies during earthquakes.
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Old 10-21-2017, 11:29 PM
Darren Garrison Darren Garrison is offline
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Originally Posted by Chronos View Post
This naturally put most of the Earth's gold in the core; it's only occasionally that volcanic activity brings some to the surface.
Most volcanoes are very shallow, with all melted rocks coming from lower parts of the crust itself (or maybe the upper mantle) coming nowhere near the core. Possibly all the gold found on the surface today came from asteroid strikes.

The question of gold in veins can be asked about pretty much any element or mineral found only in specific locations, and the answer is: it's complicated.
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Old 10-22-2017, 04:44 AM
Mijin Mijin is offline
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I had no idea that gold was mostly made by merging neutron stars.
In fighting my own ignorance, I came across this neat periodic table of elements, color-coded by origin (SVG link).
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Old 10-22-2017, 08:12 AM
ftg ftg is offline
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This is fairly new to me.

What I have always understood was the supernovas both produced the heavier-than-iron elements as well as dispersed them into space for later planet formation.

Would neutron star collisions be nearly as effective at this as supernovas?
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Old 10-22-2017, 08:18 AM
Chronos Chronos is offline
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Neutron star collisions are supernovas. Or at least, one kind of them.
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Old 10-22-2017, 08:59 AM
Lucas Jackson Lucas Jackson is offline
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Originally Posted by Darren Garrison View Post
Possibly all the gold found on the surface today came from asteroid strikes.
That's an interesting and compelling article but if true makes the existence of gold veins even more mysterious to my mind.
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Old 10-22-2017, 09:29 AM
Riemann Riemann is online now
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Quote:
Originally Posted by Chronos View Post
Neutron star collisions are supernovas. Or at least, one kind of them.
To expand on this: Since "nova" refers to the appearance of a new visible star, from an observational perspective any transient light source falls into the category. However, I think an astrophysicist would not usually include mergers into the category "supernova", at least not without qualification. "Kilonova" has been coined for these massive mergers.

https://en.wikipedia.org/wiki/Kilonova

Last edited by Riemann; 10-22-2017 at 09:30 AM.
  #10  
Old 10-22-2017, 09:45 AM
John DiFool John DiFool is offline
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Originally Posted by Chronos View Post
Neutron star collisions are supernovas. Or at least, one kind of them.
But much rarer. That would imply if the sun formed from a nebula where such a collision never took place, the amount of gold on the planet would be very meager.
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Old 10-22-2017, 11:44 AM
Darren Garrison Darren Garrison is offline
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Originally Posted by Lucas Jackson View Post
That's an interesting and compelling article but if true makes the existence of gold veins even more mysterious to my mind.
Oversimplifying it (and I'm no geologist/mineralogist myself) it is chemistry and physics. We get veins of gold for similar reasons that we get frost on windows and pillars of salt in the Dead Sea. Gold exists in a location and condition that allows it to be dissolved, then moves to a new location without the same conditions and precipitates out. The same goes for the quartz it is associated with. Gold veins are essentially especially blingy geodes.
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Old 10-22-2017, 11:49 AM
Precambrianmollusc Precambrianmollusc is offline
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For what it is worth this article popped up on my linkedin feed regarding how gold gets to certain deposits from the magma.

http://www.geologypage.com/2017/10/p...provinces.html

Its not a hugely non geologist friendly article and a summary appears to be ..
"Thus, the generation of Au deposits in the crust may result from the conjunction in time and space of three essential factors: an upper mantle or lower crustal source region particularly enriched in Au, a transient remobilisation event and favourable lithospheric-scale plumbing structures."

Whatever that may mean, but the article has some graphics that may help. The article does indicate this is a competing theory to others that are out there.
  #13  
Old 10-22-2017, 03:33 PM
Napier Napier is offline
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Originally Posted by Mijin View Post
I had no idea that gold was mostly made by merging neutron stars.
In fighting my own ignorance, I came across this neat periodic table of elements, color-coded by origin (SVG link).
WOW!! This is the neatest item I've seen in a long time! Nice find!!!
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Old 10-23-2017, 10:30 AM
Lucas Jackson Lucas Jackson is offline
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Originally Posted by Mijin View Post
I had no idea that gold was mostly made by merging neutron stars.
In fighting my own ignorance, I came across this neat periodic table of elements, color-coded by origin (SVG link).
Thanks for that link. Very cool!
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Old 10-23-2017, 11:00 AM
rbroome rbroome is offline
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Originally Posted by Mijin View Post
I had no idea that gold was mostly made by merging neutron stars.
In fighting my own ignorance, I came across this neat periodic table of elements, color-coded by origin (SVG link).
That is a cool table!
I learned about s-Process of element formation in Sixty Symbols and it goes into some detail:
https://www.youtube.com/watch?v=KlBG_A4Djp4

It shows how many of the heavy elements are made inside stars including neutron stars.
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Old 10-23-2017, 01:08 PM
Hooleehootoo Hooleehootoo is offline
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With so many neutrons, one would expect the fissionable elements to be splitting at the same time as other processes are creating Th, U, Pu, right?
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Old 10-23-2017, 04:41 PM
Chronos Chronos is offline
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With a neutron star collision, pretty much all processes are going on at once. They're not all going at the same rate, though, so in the end once everything cools down, you'll have a mix of elements in various proportions.
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Old 10-25-2017, 04:28 PM
zimaane zimaane is offline
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If a neutron star is made up of, you know, neutrons, where do the protons in the synthesized gold nuclei come from ?
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Old 10-25-2017, 04:39 PM
Exapno Mapcase Exapno Mapcase is offline
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Originally Posted by zimaane View Post
If a neutron star is made up of, you know, neutrons, where do the protons in the synthesized gold nuclei come from ?
Free neutrons will naturally decay into a proton, electron, and an electron anitneutrino. Gravity forces the neutrons to remain stable in a neutron star. Disrupt that and lots of energy (the scientific term is "oodles") is available to break down neutrons and build up just about anything.
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Old 10-25-2017, 04:42 PM
Darren Garrison Darren Garrison is offline
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Originally Posted by zimaane View Post
If a neutron star is made up of, you know, neutrons, where do the protons in the synthesized gold nuclei come from ?
From neutrons decaying into protons, electrons, and various other debris once a chunk of the neutron star too small to remain neutronium is chipped off the star.
  #21  
Old 10-25-2017, 08:16 PM
Chronos Chronos is offline
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Even while it's still in the star, a neutron star still contains some protons (about 10% of the mass), with a corresponding number of electrons. Plus there are also thin outer layers which still contain discrete atoms (though some of them in isotopes which would be impossible at low pressures).
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Old 10-26-2017, 12:52 AM
j_sum1 j_sum1 is offline
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Even while it's still in the star, a neutron star still contains some protons (about 10% of the mass), with a corresponding number of electrons. Plus there are also thin outer layers which still contain discrete atoms (though some of them in isotopes which would be impossible at low pressures).
Ok. So you are telling me that the stuff of a neutron star would conduct electricity. I confess that this is not something I have really thought of before.


I had always pictured neutron stars as being dense, spherical, featureless, hideous, potentially dangerous but mostly passive entities. If they contain charged particles that affords them some properties I had not really considered.
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Old 10-26-2017, 08:34 AM
Darren Garrison Darren Garrison is offline
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Ok. So you are telling me that the stuff of a neutron star would conduct electricity. I confess that this is not something I have really thought of before.
One word: plastics pulsars.
  #24  
Old 10-26-2017, 09:47 AM
zimaane zimaane is offline
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Even while it's still in the star, a neutron star still contains some protons (about 10% of the mass), with a corresponding number of electrons. Plus there are also thin outer layers which still contain discrete atoms (though some of them in isotopes which would be impossible at low pressures).
So the pressure of gravity in a neutron star is strong enough to hold together isotopes that would otherwise be unstable? Wow, the universe is weird
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Old 10-26-2017, 10:01 AM
k9bfriender k9bfriender is offline
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Originally Posted by j_sum1 View Post
Ok. So you are telling me that the stuff of a neutron star would conduct electricity. I confess that this is not something I have really thought of before.


I had always pictured neutron stars as being dense, spherical, featureless, hideous, potentially dangerous but mostly passive entities. If they contain charged particles that affords them some properties I had not really considered.
Not just conduct, I believe that neutron stars are supposed to be superconductors.

Dense, spherical, and dangerous you got for sure. Hideous is in the eye of the beholder.

Featureless (counting magnetic fields) and passive, not so much.
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Old 10-26-2017, 10:33 AM
Darren Garrison Darren Garrison is offline
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So the pressure of gravity in a neutron star is strong enough to hold together isotopes that would otherwise be unstable? Wow, the universe is weird
A neutron star is a little like one big unstable isotope with an atomic weight of 1.73 kazillion.

(ETA: Just had a thought--a mole of neutron stars!)

Last edited by Darren Garrison; 10-26-2017 at 10:34 AM.
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Old 10-26-2017, 11:15 AM
Machine Elf Machine Elf is offline
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(ETA: Just had a thought--a mole of neutron stars!)
How about a mole of moles?
  #28  
Old 10-26-2017, 11:32 AM
Darren Garrison Darren Garrison is offline
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If I'm doing my math right, it would take around 100 million moles of moles to collapse into a neutron star.
  #29  
Old 10-26-2017, 11:57 AM
Machine Elf Machine Elf is offline
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If I'm doing my math right, it would take around 100 million moles of moles to collapse into a neutron star.
No, it's got to be way more than that; I've got that many in my backyard right now, and I haven't seen any neutron stars in the area.
  #30  
Old 10-26-2017, 04:37 PM
Chronos Chronos is offline
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Quote:
Quoth j_sum1:

I had always pictured neutron stars as being dense, spherical, featureless, hideous, potentially dangerous but mostly passive entities. If they contain charged particles that affords them some properties I had not really considered.
The extent to which it affords them properties beyond what you'd considered is really quite difficult to fathom. For instance, you can have neutron stars whose magnetic fields are a billion times denser than water. Note: That's not the matter of the star (which is orders of magnitude denser yet than that); that's literally the density of the magnetic field alone.
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