[meteorite-list] Fusion Crust on Irons--Not

From: debfred at att.net <debfred_at_meteoritecentral.com>
Date: Thu, 19 Nov 2009 23:20:07 +0000
Message-ID: <111920092320.12242.4B05D2A70000D1F700002FD222230706129B0A02D29B9B0EBF0B0A9D000D0A0B_at_att.net>

  Carl, I need some help here. Which one of these elements or minerals is in the silicate group?
Sikhote-Alin is a coarse iron octahedrite. Its composition is as follows: 5.9% nickel, 0.42 % cobalt, 0.46% phosphorus, 0.28% sulfur, smaller amounts of germanium and iridium, and the remainder (approximately 93%) is iron. The following minerals are present: taenite, plessite, rhabites, troilite, chromite, kamacite, and schreibersite crystals. ...
Regards, Fred
-------------- Original message ----------------------
From: <cdtucson at cox.net>
>
If I'm not mistaken. The crust shown on Sikhotes may well be a true fusion crust
> because sikhote does contain some silicate minerals within it.
It is the irons without silicates that cannot produce a true fusion crust. And
as Elton said, Nobody has ever shown one of these non-silicate irons with fusion
crust. In fact the two examples shown are the only examples I have ever seen of
any type of iron meteorite with fusion crust, not counting true silicated irons
> of course.
Does anyone have other pictures of any irons with fusion crusts to share? Thanks
> Carl
> --
> Carl or Debbie Esparza
> Meteoritemax
>
>
> ---- ensoramanda at ntlworld.com wrote:
> > Hi Elton,
> >
> I think it is that thin coating of magnetite that most folks are calling a
> fusion crust on fresh irons...what else can it be called?
> >
> As you say, unfortunately it is quite fragile and on most irons it flakes or
comes off after very little time in our climate, so most of those wonderful
> looking sikhote alins at the shows have actually been cleaned and treated and
> have lost the magnetite 'fusion crust'. I have seen many with remnants which you
> can see still peeling off but rarely in their pristine matt grey original state.
> Also, as you say, those flow lines can be still present mostly underneath when
> the magnetite/crust has gone but are I think much more detailed and sharp when
> the magnetite coating is fresh.
> >
> > If you know of a different name/term to call the magnetite coating on fresh
> irons other than fusion crust then I am sure we would all like to know what we
> should call it?
> >
> > Regards,
> >
> > Graham
> >
> >
> >
> > ---- MEM <mstreman53 at yahoo.com> wrote:
> > > Stopping in a few minutes to state again that all this discussion about
> fusion crust on irons is right next to unicorns postulations. Everyone says
> that fusion crust on irons exists but no one can come up with the proof.
> Non-silicate bearing irons DO NOT/CANNOT have FUSION crust: they have a very
> fragile magentite micro-crystal "film" and they have an ablation surface but,
> they can't by definition have a "fusion crust" and no matter whom the expert
> quoted they still do not have a fusion crust. A fusion crust has to have a
> silicate source to for the glass component of the crust-- Nada, Nix, No How.
> > >
> > > Both silicate and non-silicate meteorites have an ablated/ablation surface,
> and they can show flight features--but not all meteorites have a fusion crust.
> I have some OCs which have flow lines UNDER the fusion crust remnants.
> > >
> > > If anyone still defends the presence of fusion crust on (non-silicate
> bearing) irons then show me the "crust"...can't?..ok show me the glass? ....
> right then-- no photos, no thin sections, no micro graphs???......And while
> there was one close up of an ablated surface showing soft wavy lines of briefly
> melted metal that was aligned to aerodynamic vectors--This does not fusion crust
> make.
> > >
> > > Unlike in politics and public opinion, in science, no matter how often an
> untruth is repeated it doesn't become "truth" by majority belief. But science,
> being a human endeavor, sometimes can find itself "off track" and when it does
> it accepts the error and gets back on track.
> > >
> > > Elton
> > > ______________________________________________
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> >
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Received on Thu 19 Nov 2009 06:20:07 PM PST