[meteorite-list] NEW FALL

From: jason utas <jasonutas_at_meteoritecentral.com>
Date: Sun, 10 Jun 2012 18:40:11 -0700
Message-ID: <CAK837U1fNPmT1bPihr4XChXhJJYpjCbQO3g8RC7PbtJ13DRgaw_at_mail.gmail.com>

Hello Graham, All,
Krinov concluded that all of these features we call "craters" are in
fact small pits caused by the vaporization of more volatile inclusions
under the fusion crust of the iron.

In other words, you have a heat-affected zone under the surface of the
iron, and if you get a more volatile inclusion, it can be heated to
the point that it vaporizes/expands, creating a small
explosion...."crater" in the overlying soft/molten metal.

This would explain the vast number of such "craters" seen on Franconia
irons -- since those specimens contain large amounts of disseminated
stony particles and troilite, it makes sense that they would contain a
greater number of inclusions that might create such features (versus a
relatively homogeneous Sikhote-Alin).

The exception to this rule would be craters formed on shrapnel, but
most of those supposed craters I've seen appeared to be exposures of
where round (troilite) inclusions had been. The "raised rims"
appeared to form from the shear/fracture propagating towards the weak
point in the meteorite (the inclusion), creating a surface that gently
sloped upwards to a smooth, round cavity.

I've seen a few exceptions, but not many.

Regards,
Jason

> ---------- Original Message ----------
> From: Graham Ensor <graham.ensor at gmail.com>
> Date: Sun, Jun 10, 2012 at 6:28 PM
> Subject: Re: [meteorite-list] NEW FALL
> To: MICHAEL JOHNSON <rockmansc at yahoo.com>
> Cc: "meteorite-list at meteoritecentral.com" <meteorite-list at meteoritecentral.com>
>
>
> Wow! where is that from Michael/Mike? Strange that it has so many
> small impacts on the oriented ablated leading edge and weird chisel
> marks too? Looks like some satellite debris I've seen before but the
> stoney and pyroxene inclusions plus the entry speed it would have had
> seem to rule that out.
> Curious.
>
> Graham
>
> On Mon, Jun 11, 2012 at 1:30 AM, MICHAEL JOHNSON <rockmansc at yahoo.com> wrote:
>> http://www.rocksfromspace.org/new-fall-2012.html
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Received on Sun 10 Jun 2012 09:40:11 PM PDT