[meteorite-list] Fusion Crust on Irons

[Dave Freeman mjwy]

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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