[meteorite-list] iron meteorite cooling rates and Meteorite Men

[Richard Montgomery]

Hi List.  (ot a chemist, me, just a collector, not ametorologist, just a 
passionate meteorite guy.

This is mostly a question from Allan's post just now:  I was always under 
the impression that  iron meteorites resulted from colliding differentiated 
parent-bodies, and that the crystallization sequence was achieved after an 
impact that exposed a core, molten NiFe suddenly ejected into space without 
the shield of its former silicate mantle.  Am I way off base?  Does Thompson 
structure develope within?


----- Original Message ----- 
From: "Alan Rubin" <aerubin at ucla.edu>
To: <meteorite-list at meteoritecentral.com>
Sent: Wednesday, December 15, 2010 4:21 PM
Subject: Re: [meteorite-list] iron meteorite cooling rates and Meteorite Men


> The iron meteorite cooling rates generally range from about 1 - 100ºC/Myr.
> The reason for such slow rates is that the metal cores are buried deeply
> within silicate mantles and heat cannot readily escape.  The coarseness of
> the Widmanstatten pattern is a function of cooling rate -- more slowly
> cooled irons will develop thicker kamacite lamellae.  But there are two
> other factors that govern the coarseness of the structure -- the Ni
> concentration and the nucleation temperature.  The lower the Ni
> concentration in the metal, the more kamacite will develop upon cooling.
> Metal that begins to nucleate at a higher temperature will have a longer
> period within which kamacite can grow.
>
>
>
>
>
> Alan Rubin
> Institute of Geophysics and Planetary Physics
> University of California
> 3845 Slichter Hall
> 603 Charles Young Dr. E
> Los Angeles, CA  90095-1567
> phone: 310-825-3202
> e-mail: aerubin at ucla.edu
> website: http://cosmochemists.igpp.ucla.edu/Rubin.html
>
> ______________________________________________
> Visit the Archives at 
> http://www.meteoritecentral.com/mailing-list-archives.html
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>