[meteorite-list] a question on fusion crust

From: Michael Farmer <meteoriteguy_at_meteoritecentral.com>
Date: Thu, 22 Mar 2007 09:48:00 -0700 (PDT)
Message-ID: <87052.81468.qm_at_web33114.mail.mud.yahoo.com>

But made from the matrix component. burned material
from the parent body, regardless of how it is
chemically changed, same as the fusion crust on any
meteorite. Take a Eucrite like Stannern for example,
white interior, yet the fusion crust is glossy black.
That is not soot, it is chemically altered matrix.
Nothing more.
Michael Farmer
--- Armando Afonso <armandoafonso at oniduo.pt> wrote:

> Obviously, it is a diferent material...
> The external fusion crust of iron meteorites is
> Magnetite, the result of the
> combination with the air`s oxygene.
> AA
>
>
> ----- Original Message -----
> From: "Michael Farmer" <meteoriteguy at yahoo.com>
> To: "Mr EMan" <mstreman53 at yahoo.com>; "Michael
> Murray"
> <mmurray at montrose.net>;
> <Meteorite-list at meteoritecentral.com>
> Sent: Thursday, March 22, 2007 4:14 PM
> Subject: Re: [meteorite-list] a question on fusion
> crust
>
>
> > This is simple.
> >
> > Fusion, the result of material burning at extreme
> > temeratures, and crust, the layer on the surface
> that
> > was not there before re-entry.
> > Thus, FUSION CRUST
> > It is quite obvious that the surface of a freshly
> > fallen iron, with the blue-black coating is a
> FUSION
> > CRUST.
> > It generally can't be "wiped" off. I have pieces
> in my
> > collection, Bugoslava for example, with a .5 mm
> layer
> > of blue-black fusion crust, that survived cutting
> and
> > polishing of the meteorite, so it is not exacly
> > "soot". Of course the crust is the same as the
> parent
> > material, even on stones. How could it be of a
> > different material? How could an object, falling
> > through the atmosphere, get coated with anything
> but
> > it's own matrix as it burns? Yes, the silicates
> can be
> > altered due to heating, while irons tend not to
> > chemically alter.
> > Elton, I think you are about the only one in the
> world
> > that thinks fresh fallen iron meteorites do not
> have
> > fusion crust.
> > Michael Farmer
> >
> > --- Mr EMan <mstreman53 at yahoo.com> wrote:
> >
> >> The "soot" coating you are talking about is
> mostly
> >> freshly created magnetite (micro /nano crystals)
> >> from
> >> the oxidation of iron whilst passing through the
> >> incandescent phase. It adheres by magnetism and
> can
> >> be wiped off with rough handling. There is
> probably
> >> a
> >> carbon component however graphite turns to carbon
> >> dioxide upon burning >
> >> There are several other terms for the zone
> >> associated
> >> with "ablation" heating, one of which is in the
> >> literature: "zone of thermal alteration". When
> there
> >> is an oxidation coat
> > .
> > native elements such as
> >> found
> >> on sodium or phosphorus it is sometimes called a
> >> rind.
> >> This is what I favor to describe the coatings on
> >> irons--the one before terrestrial oxidation also
> >> known
> >> as rust.
> >>
> >> In my view there can be no crust when the
> chemical
> >> and
> >> physical characteristics of the surface do not
> >> differ
> >> from the donor material. That lets the door open
> >> for
> >> irons having crust and at least most agree that
> it
> >> is
> >> unlike the fusion crust of stoney meteorites.
> >>
> >> While at the Smithsonian inspecting the
> collection
> >> up
> >> close and personally, I was advised to use
> caution
> >> in
> >> examining a fresh iron as the coating would rub
> off
> >> easily. They didn't call it fusion crust but the
> >> issue
> >> never came up. The point being, not everyone is
> in
> >> agreement nor is there universal usage.
> >>
> >> Critical analysis on the assumptions about fusion
> >> crust on irons would likely lead to a more
> >> descriptive
> >> table of composition and relate that to the
> >> metallurgy
> >> and chemical composition of the meteorite itself.
> In
> >> fact I believe research on crustal petrology
> would
> >> be
> >> reveling for all types of meteorites. I yet
> wonder
> >> why
> >> some lunarites have a brown bubbly crust. The
> crust
> >> of
> >> a iron meteorite on Mars will be different from
> one
> >> here and I'd like to know what to expect and why.
> >>
> >> Intuitively, I know there would be rare minerals
> >> such
> >> as nickel oxides,nitrates, phosphates perhaps
> even
> >> a
> >> sulphide and yes even O3 and O4 silicates.
> However
> >> current wisdom is that crust is crust ego no
> >> research
> >> needs to be contemplated-NOT.
> >>
> >> Some of the oft quoted god status experts who
> write
> >> of
> >> fusion crust on irons monitor this list and have
> >> remained curiously silent on the topic. I hope
> this
> >> topic is thought provoking for all parties.
> >>
> >> I suppose that the use of the term "fusion crust"
> >> universally with respect to irons is acceptable
> if
> >> one
> >> doesn't have a need for technical accuracy. One
> >> thing
> >> yet to be refuted here on the list is that the
> >> "crust"
> >> on irons is not composed of "glass".
> >>
> >> Elton
> >>
> >> --- Michael Murray <mmurray at montrose.net> wrote:
> >>
> >> > Hi List,
> >> > Are you ready for a dumb question! Here
> goes...
> >> Is
> >> > there a more definitive description of the
> >> blackened outer layer on the surface of iron
> >> meteorites than simply referring to it as "fusion
> >> crust"? From what I can gather looking at
> different
> >> pictures of stonys, they seem to have a glassy
> or
> >> melted layer of the material of the stone. I can
> >> see
> >> that being a 'crust'. On at least some irons,
> there
> >> is a coating but it doesn't appear glassy, just
> >> blackened. I'm guessing that that coating is
> >> partially resulting from burning of the gases in
> the
> >> atmosphere? If it is a 'crust', it is not much
> of
> >> one. It looks
> >> like a very thin coating of soot that is adhered
> to
> >> the stone, although more durable than soot.
> This
> >> is
> >> probably one of those dumb questions that the
> >> Collection of Wisdom would answer.
> >>
> >> The stone in this picture has the blackened
> layer
> >> I'm referring to:
> >>
> >
>
<http://i127.photobucket.com/albums/p124/mmurray_02/IMG_0319.jpg>
> >> Michael Murray
> >> ______________________________________________
> >> Meteorite-list mailing list
>
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Received on Thu 22 Mar 2007 12:48:00 PM PDT