[meteorite-list] Atmospheric ablation marks on Tektites?

From: mexicodoug at aim.com <mexicodoug_at_meteoritecentral.com>
Date: Sat, 05 Apr 2008 11:37:03 -0400
Message-ID: <8CA654A07C5DDCB-208-2E15_at_FWM-D33.sysops.aol.com>

Hi Norm,

Running a little slow in my emails, thanks for the (much earlier) reply
and nice to see you're still in touch...

Best wishes,
Doug

-----Original Message-----
From: Norm Lehrman <nlehrman at nvbell.net>
To: Michael Gilmer <michael_w_gilmer at yahoo.com>;
meteorite-list at meteoritecentral.com
Sent: Fri, 4 Apr 2008 9:16 pm
Subject: Re: [meteorite-list] Atmospheric ablation marks on Tektites?



Mike,

I'm not aware of any LDG that retains preserved
external primary skin, so we don't even know what
morphology or skin LDG may have once had. What you
see now is mostly the result of desert sand-blasting
by saltating sand grains. It can look "oriented", and
indeed it is, but with respect to prevailing surface
winds, not atmospheric re-entry. Many pieces of LDG
can properly be termed "ventifacts".

The australasians, and in particular, the australites
certainly do have all sorts of thermal ablasian
features, and when it comes to orientation, flanged
buttons exceed the perfection of any meteorite. This
is "orientation" exactly as we intend the word in
meteoritics.

With tektite discussions, one answer rarely fits
all---

Cheers,
Norm
(of http://tektitesource.com , temporarily on hold
while we are stationed in Tanzania for a few years).
--- Michael Gilmer <michael_w_gilmer at yahoo.com> wrote:

> Hi Group!
>
> While reading through another Meteorite-related
> message board on the WWW, I ran across a statement
> by
> an IMCA member that puzzles me somewhat. A
> discussion
> about Libyan Desert Glass was ongoing, and we were
> sharing photos of our LDG specimens. (and I showed
> off my new 9+ gram piece of dark-veined glass from
> Michael Farmer - thanks Mike!)
>
> So the guy says :
>
> "This is one of my favorites and is fully oriented
> with regmaglypts (yes, tektite impactites can have
> atmospheric ablation patterns too)."
>
> Ok, here is my confusion - I was under the
> impression
> that tektites were formed on impact - on Earth. So,
> doesn't this mean they cannot have atmospheric
> ablation patterns? Assuming the tektite never
> passed
> through the atmosphere, I don't see how this is
> possible.
>
> I have seen tektites with features that resemble
> regmaglypts and orientation, but this is just chance
> occurence, right?
>
> Or do I need to be schooled here?
>
> Thanks in advance!
>
> MikeG
>
>
>
>
>
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Received on Sat 05 Apr 2008 11:37:03 AM PDT