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

From: ensoramanda at ntlworld.com <ensoramanda_at_meteoritecentral.com>
Date: Thu, 19 Nov 2009 11:29:42 +0000
Message-ID: <20091119112942.558H0.942523.root_at_web02-winn.ispmail.private.ntl.com>

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
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
Received on Thu 19 Nov 2009 06:29:42 AM PST