[meteorite-list] Fusion Crust on Irons

From: Dave Freeman mjwy <dfreeman_at_meteoritecentral.com>
Date: Mon, 04 Dec 2006 12:09:23 -0700
Message-ID: <45747263.8070307_at_fascination.com>

Would "shikote Alin"-like crust work? Blue steel, burn baby burn!
Dave F.

MexicoDoug wrote:

>Hi Gary,
>
>Fusion crust can be in the eyes of the beholder, so the difficulty with this
>question is we are making a one-size fits all definition.
>
>For the irons, you could get a verrrry thin local destruction of any
>crystalline patterns or figures (no longer etch), some chemical change from
>'burning' up including colors. In the case of stones, it is a different and
>typically a glazed-silicate ceramic crust forms. It can get a rainbowish
>tint from burnishing, though it usually looks somewhat bluish. It's so thin
>that it quickly is lost to other mineralization in the oxidizing humid
>environment that is earth's.
>
>So there is a difference. But loosely thay can all be attributed to
>'fusion' though in the case of iron it has a different characteristic. In
>either case, when the fusion crust is black, this is generally caused by
>oxidized iron during the entry, not terrestrialization. That is a main
>difference between what we see on many older irons in dry and stable
>environments.
>
>So, yes, irons can have a fusion crust, it is just not predominantly a
>ceramic kiln glaze best seen from some achondrites, which is the classic...
>
>Best wishes, Doug
>
>
>----- Original Message -----
>From: "Gary K. Foote" <gary at webbers.com>
>To: <Meteorite-list at meteoritecentral.com>
>Sent: Monday, December 04, 2006 1:26 PM
>Subject: [meteorite-list] Fusion Crust on Irons
>
>
>
>
>>Hi All,
>>
>>Recently I have read a few posts to this list that definitively claim that
>>irons do not form a fusion crust. Yet, in Norton's "Rocks From Space",
>>[pg 167 in my softbound edition] it clearly states the following;
>>
>>"Iron meteorites have the thinnest crust of all, usually only a small
>>fraction of a millimeter thick. A fresh crust is blue-black to black and
>>looks like freshly welded steel. This crust is fragile and easily
>>destroyed if the meteorite weathers for even a short time."
>>
>>So, which is true? Crust or no crust for irons?
>>
>>Gary Foote
>>http://www.meteorite-dealers.com
>>
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>>
>>
>
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Received on Mon 04 Dec 2006 02:09:23 PM PST