[meteorite-list] Is there room for a meteorite question ?

From: E. L. Jones <jonee_at_meteoritecentral.com>
Date: Thu Apr 22 10:17:42 2004
Message-ID: <3FD5CEB2.5020908_at_epix.net>

Hello Lars,

The cooling speed must remain within the limits of a few degrees per
million years for the nickel atoms to migrate and align. I think the
temperature bands where Widmanstätten pattern (i.e. taenite/kamacite
lattices) can occur is between 1400° and 800°C. (pressure relative).
Above 1400° is molten and below 800° only kamacite forms.

The width of the spaces are directly related to cooling duration. Finer
lattice indicates a shorter cooling cycle. The bands /pattern will
remain at what ever level they were if cooling suddenly drops below 800°C..

To my knowledge the Rare Earth Element (REE) chemistry values haven't
been cross matched between fine to course. That is no evidence links
any of the iron classes to any common parent body. Someone may have now
checked this as my research is old.

Intuitively, it seems to make sense that there is a gradient from core
to surface, however the high thermo-transmission co-effecients of nickel
-iron might keep an average sized asteroid even tempered. perhaps
someone else has detailed information. Does anyone have information
about common parent bodies for Iron meteorites?

Regards,
Elton


Lars Pedersen wrote:

>I was just looking at the Widmanstätten pattern on a few of my iron-slices
>
>I was wondering if anyone know if the cooling speed of the asteroid core has
>something to do with the pattern (from fine toward coarse) ?
>
>I thought that maybe the coarser types maybe are from deeper in the core ?
>
>My english is not the best but I hope you understand what I mean.
>
>Best wishes
>Lars Pedersen
>
>
>
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Received on Tue 09 Dec 2003 08:31:30 AM PST