<p>The process of <a href="https://en.wikipedia.org/wiki/Planetary_differentiation" rel="noreferrer">differentiation</a> is how metals like iron and nickel can become separated from less dense substances. It generally occurs in large, partly solid bodies in the early solar system, whose interiors are melted either via accretion energy, radioactivity or some combination of the two. A solid iron meteor is likely a fragment of a differentiated larger body that has been disrupted by a collision.</p>

<p>I think what you are asking is why such a differentiation process does not occur in the primordial disc from which the solar system formed. The answer lies in turbulence and other mixing mechanisms that act against differentiation. If the mixing timescale in the disc is shorter than the differentiation timescale then the differentiation just won't occur. This is for example the same reason that stars like the Sun do not have all their heavy chemical elements at the core.</p>

CC BY-SA 4.0
2019-06-17T19:51:19.523Z
I thought I had marked this answer as accepted. Seems fairly reasonable.
Tom Russell
CC BY-SA 4.0
2019-06-11T15:10:16.027Z
2019-06-11T15:10:16.027Z
ProfRob
<p>I guess that's pretty much it. I just heard that that a meteor fragment was found to be solid iron and it just seems inexplicable that it was floating around.</p>

CC BY-SA 4.0
2019-06-11T16:35:44.977Z
What Rob says. But quite a large percentage of the solar system's heavy elements *are* in the Sun. Eg, the mass of iron in the Sun is around 460 times the total mass of the Earth, using this data from [hyperphysics](http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/suncomp.html) and Google calculator (which has handy constants like the mass of the Sun & Earth built in).
PM 2Ring
CC BY-SA 4.0
2019-06-12T07:39:51.083Z
-1 Because, Why should they?
Zaibis
<solar-system><meteorite><accretion-discs>
Why didn't all the iron and heavier elements find their way to the center of the accretion disc in the early solar system?
Tom Russell
# Why didn't all the iron and heavier elements find their way to the center of the accretion disc in the early solar system?

(Asked by: username_0 on 2019-06-11)

I guess that's pretty much it. I just heard that that a meteor fragment was found to be solid iron and it just seems inexplicable that it was floating around.

**Tags:** solar-system, meteorite, accretion-discs

> **Comments:**
> **username_1**: What Rob says. But quite a large percentage of the solar system's heavy elements *are* in the Sun. Eg, the mass of iron in the Sun is around 460 times the total mass of the Earth, using this data from [hyperphysics](http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/suncomp.html) and Google calculator (which has handy constants like the mass of the Sun & Earth built in).  
> **username_2**: -1 Because, Why should they?  

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## 1 answers

### Answer by username_3 on 2019-06-11. Score: 13 | Accepted answer

The process of [differentiation](https://en.wikipedia.org/wiki/Planetary_differentiation) is how metals like iron and nickel can become separated from less dense substances. It generally occurs in large, partly solid bodies in the early solar system, whose interiors are melted either via accretion energy, radioactivity or some combination of the two. A solid iron meteor is likely a fragment of a differentiated larger body that has been disrupted by a collision.

I think what you are asking is why such a differentiation process does not occur in the primordial disc from which the solar system formed. The answer lies in turbulence and other mixing mechanisms that act against differentiation. If the mixing timescale in the disc is shorter than the differentiation timescale then the differentiation just won't occur. This is for example the same reason that stars like the Sun do not have all their heavy chemical elements at the core.

> **Comments:**
> **username_0**: I thought I had marked this answer as accepted. Seems fairly reasonable.  

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