[meteorite-list] Is there room for a meteorite question ?

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From: MexicoDoug_at_aol.com <MexicoDoug_at_meteoritecentral.com>
Date: Thu Apr 22 10:17:45 2004
Message-ID: <11a.2c2d3e0c.2d0aa15a_at_aol.com>

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And for a more complete stab at answering your question from a proud=20
"newbee". Note you really asked two questions. =20

1. If upon cooling there is expansion and 2. If the density is the same as=20
non-crystalline materials formed on earth in the same ally proportions.=20

To question 1: If I understand your question properly at first reading you=20
think that Fe-Ni mixtures upon cooling in the proper proportions forming tae=
nite=20
/ kamacite might expand? No way. Those structures do not form until after=20
the alloy is already solid, though in an amorphous (non-crystalline) state w=
ith=20
selective atom mobility. Those migrations of atoms occur to release heat=20
energy flowing out of the system because of decreasing boundary temperatures=
and=20
the law of heat flowing from higher to colder temperatures. The migrations=20
are happening as these new crystal structures settle down from vibrations an=
d=20
fall into their little unit cells, allowing for a more dense material. For=20=
an=20
expansion they would have to rip apart the already developed solid=20
structure...causing perhaps a very brittle substance even.

Now your other question, whether the "terrestrial" amorphous material has th=
e=20
same density as a "crystalline" meteorite material. That's something I'm=20
sure you know if you think a minute. Of course it does not have the same=20
density. So save your iron meteorites for better experiments, and don't mel=
t them to=20
see. The amorphous material probably won't even have as an extremely=20
precisely definable density. It ought to vary because it is amorphous. Whe=
ther=20
statistics averages the density out or not is a separate question and of cou=
rse=20
will depend on exactly what alloy %'s you have and how well they are mixed o=
n a=20
macro scale...the history of how the sample was cooled, etc. Does graphite=20
have the same density as diamond? No.

You cite water, when freezing, as expanding as your model, since water (0.92=
=20
g/mL) in equilibrium at 0=C2=B0C is denser than ice (1.00 g/mL). Water is w=
eird,=20
and one of the anomalous things that explains life. The short answer on why=
it=20
expands upon decreasing temperature at atmospheric pressure from 4=C2=B0C to=
0=C2=B0C=20
is a softening of proton (hydrogen) bonding and disruption of that nicely=20
organized structure as it is an ionic (solution) type attraction that is des=
troyed=20
as the molecules begin to fall down from their bounciness caused by higher=20
temperatures. So the destruction of the hydrogen bonds happens upon cooling=
. =20
Another way to say that is the melting of the hydrogen bonds upon cooling=
=E2=80=A6 In=20
its amorphous, hydrogen-bondless state oxygen atoms find themselves not=20
tolerating such close density as before when all were moderated by the hydro=
gen=20
atoms. So they repel each other an average of about 8% volume increase. Wa=
ter=20
would be less than 0.92 g/mL at room temperature if not for the hydrogen bon=
ding.=20
Probably about 0.90, and then it would behave like most of the other=20
molecules upon freezing.

There are no comparably scaled ionic like attractions going on in the metal=20
alloys as they cool. So there is no comparison to the special case of water=
. =20
Additionally, you should know that water ice has about 20 described=20
crystalline structures, and they are, not coincidentally, not all the same d=
ensity! You=20
need to know the history of it. Do you think super cooled hail is the same=20
as the cubes floating in your ice tea? No. And the rockhounds can probably=
=20
come up with a good list of structures with different densities but the same=
=20
molecular proportions.

Every sample is individual: so back to the meteorite experiment. Each=20
meteorite has a different history as in temperatures and pressures. Each ha=
s=20
different impurities, so you will need to do more that just reproduce the al=
loy=20
proportions...actually by now it seems pretty clear that the proposed experi=
ment=20
is not a good idea. All those impurities disrupt perfect conditions. So=20
oceans don't freeze at 0=C2=B0C, they are a few degrees colder, because of t=
he=20
impurities. All that affects densities, not to mention any molecular flatul=
ence=20
causing micro pores, uniformly or not. Ooops. Just checking to see if anyo=
ne read=20
this far...

PS Ice floats. Can you imagine solid pieces of metal alloy floating as it i=
s=20
melted...that was the easier explanation...

Saludos
Doug Dawn
Mexico

En un mensaje con fecha 12/11/2003 2:58:13 PM Mexico Standard Time,=20
khill_at_cpsmedical.com escribe:

>=20
>=20
>=20
> Question: When water turns to ice the change to a crystal structure
> expands the volume (decreases density). Does this density/expansion chang=
e
> also occur with the development of taenite/kamacite
> lattices? ie. at the same temperature is the density of an iron meteorit=
e
> match the density of a "terrestrial" matching mixture that is
> "noncrystalline"? Guess you could melt down one of your irons and compare=
?
>=20
> Fly Hill
>=20
> >----- Original Message -----=20
> >From: "mark ford" <markf_at_ssl.gb.com>
> >To: <meteorite-list_at_meteoritecentral.com>
> >Sent: Tuesday, December 09, 2003 8:41 AM
> >Subject: RE: [meteorite-list] Is there room for a meteorite question ?
> >
> >
> >>
> >>
> >>
> >>
> >>
> >>On the same note, thermal expansion...
> >>
> >>Presumably as the core solidifies (cools down) it would contract, would
> >>it not?, what effect would that have on the crystalline structure
> >>(widmanstatten) would there be a gradual stress/distortion in the
> >>taenite/kamacite boundries ?
> >>
> >>
> >>I guess as the core is such a big mass, any significant thermal
> >>contraction distortion would hardly be noticeable in a small hand
> >>specimen but I would imagine the thermal contraction in something the
> >>size of a large planetary body would be massive.
> >>
> >>
> >>
> >>Mark Ford
> >>
> >>
> >>
> >>
> >
> >-------------------------------------------------------------------------=
-
> >--
> >>The information contained in this email may be commercially sensitive
> >and/or
> >>legally privileged. It is intended solely for the person(s) to whom it
> is
> >>addressed. If you are not a named recipient, you are on notice of its
> >status.
> >>Please notify the sender immediately by reply e-mail and then delete
> this
> >>message from your system. You must not disclose it to any other person,
> >>copy or distribute it or use it for any purpose.
>=20

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<HTML>And for a more complete stab at answering your questio=
n from a proud "newbee".  Note you really asked two questions.  <B=
R>
 
1. If upon cooling there is expansion and 2. If the density is the same as n=
on-crystalline materials formed on earth in the same ally proportions. 
 
To question 1: If I understand your question properly at first reading you t=
hink that Fe-Ni mixtures upon cooling in the proper proportions forming taen=
ite / kamacite might expand?  No way.  Those structures do not for=
m until after the alloy is already solid, though in an amorphous (non-crysta=
lline) state with selective atom mobility.  Those migrations of atoms o=
ccur to release heat energy flowing out of the system because of decreasing=20=
boundary temperatures and the law of heat flowing from higher to colder temp=
eratures.  The migrations are happening as these new crystal structures=
settle down from vibrations and fall into their little unit cells, allowing=
for a more dense material.  For an expansion they would have to rip ap=
art the already developed solid structure...causing perhaps a very brittle s=
ubstance even. 
 
Now your other question, whether the "terrestrial" amorphous material has th=
e same density as a "crystalline" meteorite material.  That's something=
I'm sure you know if you think a minute.  Of course it does not have t=
he same density.  So save your iron meteorites for better experiments,=20=
and don't melt them to see.  The amorphous material probably won't even=
have as an extremely precisely definable density.  It ought to vary be=
cause it is amorphous.  Whether statistics averages the density out or=20=
not is a separate question and of course will depend on exactly what alloy %=
's you have and how well they are mixed on a macro scale...the history of ho=
w the sample was cooled, etc.  Does graphite have the same density as d=
iamond?  No. 
 
You cite water, when freezing, as expanding as your model, since water (0.92=
g/mL) in equilibrium at 0=C2=B0C is denser than ice (1.00 g/mL).  Wate=
r is weird, and one of the anomalous things that explains life.  The sh=
ort answer on why it expands upon decreasing temperature at atmospheric pres=
sure from 4=C2=B0C to 0=C2=B0C is a softening of proton (hydrogen) bonding a=
nd disruption of that nicely organized structure as it is an ionic (solution=
) type attraction that is destroyed as the molecules begin to fall down from=
their bounciness caused by higher temperatures.  So the destruction of=
the hydrogen bonds happens upon cooling.  Another way to say that is t=
he melting of the hydrogen bonds upon cooling=E2=80=A6  In its amorphou=
s, hydrogen-bondless state oxygen atoms find themselves not tolerating such=20=
close density as before when all were moderated by the hydrogen atoms. =
So they repel each other an average of about 8% volume increase.  Wate=
r would be less than 0.92 g/mL at room temperature if not for the hydrogen b=
onding.  Probably about 0.90, and then it would behave like most of the=
other molecules upon freezing. 
 
There are no comparably scaled ionic like attractions going on in the metal=20=
alloys as they cool.  So there is no comparison to the special case of=20=
water.  Additionally, you should know that water ice has about 20 descr=
ibed crystalline structures, and they are, not coincidentally, not all the s=
ame density!  You need to know the history of it.  Do you think su=
per cooled hail is the same as the cubes floating in your ice tea?  No.=
  And the rockhounds can probably come up with a good list of structure=
s with different densities but the same molecular proportions. 
 
Every sample is individual: so back to the meteorite experiment.  Each=20=
meteorite has a different history as in temperatures and pressures.  Ea=
ch has different impurities, so you will need to do more that just reproduce=
the alloy proportions...actually by now it seems pretty clear that the prop=
osed experiment is not a good idea.  All those impurities disrupt perfe=
ct conditions.  So oceans don't freeze at 0=C2=B0C, they are a few degr=
ees colder, because of the impurities.  All that affects densities, not=
to mention any molecular flatulence causing micro pores, uniformly or not.&=
nbsp; Ooops.  Just checking to see if anyone read this far... 
 
PS Ice floats.  Can you imagine solid pieces of metal alloy floating as=
it is melted...that was the easier explanation... 
 
Saludos 
Doug Dawn 
Mexico 
 
En un mensaje con fecha 12/11/2003 2:58:13 PM Mexico Standard Time, khill_at_cp=
smedical.com escribe: 
 
<BLOCKQUOTE TYPE=3DCITE style=3D"BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT=
: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"> 
 
 
Question:   When water turns to ice the change to a crystal struct=
ure 
expands the volume (decreases density).  Does this density/expansion ch=
ange 
also occur with the development of taenite/kamacite 
lattices?  ie.  at the same temperature is the density of an iron=20=
meteorite 
match the density of a "terrestrial" matching mixture that is 
"noncrystalline"?  Guess you could melt down one of your irons and comp=
are? 
 
Fly Hill 
 
>----- Original Message ----- 
>From: "mark ford" <markf_at_ssl.gb.com> 
>To: <meteorite-list_at_meteoritecentral.com> 
>Sent: Tuesday, December 09, 2003 8:41 AM 
>Subject: RE: [meteorite-list] Is there room for a meteorite question ?<B=
R>
> 
> 
>> 
>> 
>> 
>> 
>> 
>>On the same note, thermal expansion... 
>> 
>>Presumably as the core solidifies (cools down) it would contract, wo=
uld 
>>it not?, what effect would that have on the crystalline structure<BR=
>
>>(widmanstatten) would there be a gradual stress/distortion in the<BR=
>
>>taenite/kamacite boundries ? 
>> 
>> 
>>I guess as the core is such a big mass, any significant thermal 
>>contraction distortion would hardly be noticeable in a small hand<BR=
>
>>specimen but I would imagine the thermal contraction in something th=
e 
>>size of a large planetary body would be massive. 
>> 
>> 
>> 
>>Mark Ford 
>> 
>> 
>> 
>> 
> 
>------------------------------------------------------------------------=
-- 
>-- 
>>The information contained in this email may be commercially sensitiv=
e 
>and/or 
>>legally privileged. It is intended solely for the person(s) to whom=20=
it 
is 
>>addressed. If you are not a named recipient, you are on notice of it=
s 
>status. 
>>Please notify the sender immediately by reply e-mail and then delete=
 
this 
>>message from your system. You must not disclose it to any other pers=
on, 
>>copy or distribute it or use it for any purpose. 
</BLOCKQUOTE> 
 
</HTML>
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Received on Thu 11 Dec 2003 11:43:06 PM PST

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