[meteorite-list] Atmospheric ablation marks on Tektites?

From: Norm Lehrman <nlehrman_at_meteoritecentral.com>
Date: Sat, 5 Apr 2008 21:40:23 -0700 (PDT)
Message-ID: <87007.68634.qm_at_web81007.mail.mud.yahoo.com>

Sean & all,

This is whipping a dead horse, but I hate to see
confusion perpetuated any more than it needs to be.

You wrote "The vast majority agrees they [tektites]are
of cosmic origin--" Surely you mistakenly left out
the "NOT"? Or maybe you use the word "cosmic" to
include everything in the cosmos, which includes
earth. Most commonly though, other people use
"cosmic" to suggest something not of the earth.

There is virtually no debate about LDG. Most listees
know that we can now point to a specific source crater
(Kebira) discovered a couple of years ago.

You have and have seen "splash-form" LDG pieces???
Please don't say stuff like that in a public forum
where it can only confuse those trying to learn. I am
sure it would take about 5 minutes to find a buyer
willing to pay over $1000 for even a small (but
convincing) example, and I might well buy it myself.
Maybe consider adding the term "pseudo-splashform" to
your pseudo-regmaglypt theme.
  
"Tektite and impactite - different animals". Yes, the
words mean different things, but they are not
unrelated. Virtually all (living) students of the
subject would accept that tektites are a subdivision
of impactites. Tektites are impactites, but not all
impactites are tektites.

Deep enough,
Norm
http://tektitesource.com

--- "Sean T. Murray" <stm at bellsouth.net> wrote:

> Michael,
>
> Yep - it's amazing that something so simple as a
> piece of glass has caused
> so much churning for over 100 years. The vast
> majority agrees they are of
> cosmic origin, most believe that they are from
> impacts on earth, but there
> are still those that believe the moon is directly
> involved. I've also read
> some other bizarre ideas - the coolest of them (to
> me) was the idea that the
> reason tektites are not always formed is that maybe
> they come from the
> impact of a huge ball of silica glass that slams
> into earth - A big
> meteorite just made of glass... how cool would that
> be.
>
> So far, everything I read simply states that
> tektites come from multiple
> sources. And don't worry about the "noob" stuff -
> I've only been diving
> into this for a few months, so I'll still say
> something way off base (as
> Doug points out with my "still a lot of debate"
> comment.) It's almost
> always wrong to make any general statement about
> tektites as a whole... the
> LDG debate is still ongoing as to how it was formed,
> but most people tie it
> to an impact event, and as an impactite. I've seen
> pictures (and have a few
> pieces) of LDG that show some of the splash-form
> types of characteristics of
> tektites, but nothing with a "crust" or a true
> regmaglypts.
>
> - Tektite and impactite - different animals.
>
> - LDG and Darwin glass - Terrestrial - it really
> helps that there are
> inclusions that are of the local material stuck in
> them. They also have a
> slightly higher concentration of water (in ppm) that
> make them different
> than a true tektite. The shaping that is seen in
> those glasses is not as
> nearly as convincing as the Australasian glasses.
>
> -Ventifacts is the more correct answer. But
> considering the company that
> tektites keeps with our other cosmic collectibles,
> I'm gonna stick with
> pseudo-regmaglypts until someone beats me up.
>
> - Yes - there are a lot of good documentation that
> spells out the
> composition of tektites. (Get Povenmire's book and
> McCall's book). The
> chemical composition of the tektites is the thing
> that really drives a lot
> of the controversy. The glass, in many cases, is
> very pure and free of
> water - it's hard to say how it was made since it
> breaks a few of the glass
> making rules and regulations :) They have found
> tektite like material on
> the moon (if it was found here on earth no one would
> have argued that it was
> not a tektite), but they are very small. It was
> thought that the first
> trips to the moon would have seen and brought back
> big, standard lots of
> tektites if that is where the originated - but they
> did not. many people
> changed their minds on the lunar origin after the
> moon landings. When they
> found microtektites on the moon, they ascribed them
> to impacts on the
> moon... after all, it is generally accepted that the
> moon and the earth are
> made from each other, so there will always be
> similarities.
>
> Another fun origin note:
> John O'Keefe was another of the proponents of the
> lunar origin of tektites.
> He died in 2000, and on his funeral program he had
> wanted the following
> phrase added:
> "Tektitae De Luna Sunt!" - "tektites are from the
> moon!"
> That's conviction.
>
> Sean.
>
> ----- Original Message -----
> From: "Michael Gilmer" <michael_w_gilmer at yahoo.com>
> To: <Impactika at aol.com>
> Cc: <meteorite-list at meteoritecentral.com>
> Sent: Saturday, April 05, 2008 11:07 AM
> Subject: Re: [meteorite-list] Atmospheric ablation
> marks on Tektites?
>
>
> > Hi!
> >
> > Ok, now I figuring out this tektite issue. I want
> > to thank everyone for their kind informative
> > responses.
> >
> > First, I had no idea that tektites were so
> > controversial!
> >
> > Well, I did have *some* idea, but I thought it was
> > generally accepted by the meteorite community that
> > tektites of all types were impact artifacts and
> were
> > not the product of atmospheric-entry or
> > extra-terrestrial processes. I knew that there
> were
> > alternate theories for the origins of tektites,
> but
> > I thought these theories were mostly fringe in
> nature
> > and not commonly accepted by the Met community at
> > large. It appears I have a lot more reading to do
> > on tektites.
> >
> > "Ventifact" does indeed seem to be the best term
> > available to describe regmaglypt-like features on
> > LDG and other similar glasses. Features that
> suggest
> > orientation or flow-lines are also wind-driven
> > ventifacts I assume.
> >
> > As others said though, this does not reasonably
> > explain
> > the appearance of "button" tektites of the
> > Australite variety. Although I must admit, the
> first
> > time I saw a button-type tektite, my first thought
> > was not atmospheric-ablation or sculpting. My
> first
> > thought was a splatter-type impact artifact. If
> you
> > have ever taken a spoonfull of viscous batter and
> > dropped it on the floor, the outer edges of the
> mass
> > will spread outward while the central area is
> uplifted
> > somewhat. I had erringly assumed that similar
> > physics were at work with the button-types.
> Perhaps
> > a massive detonation on impact liquified a
> combination
> > of meteorite and earthly-minerals which were
> blasted
> > upwards and then fell back to earth - forming into
> a
> > button when the material hit the ground again.
> >
> > Again, I expose my ignorance here. And I am glad
> I
> > came to the list with this question. :)
> >
> > So while we are on the subject and educating a
> newbie
> > here, let me ask a couple of tektite-related
> questions
> > for the record, so to speak.
> >
> > 1) tektite and impactite - interchangeable terms
> or
> > different animals?
> >
> > 2) desert glass, darwin glass - terrestrial or
> not?
> >
> > 3) When describing aesthetic features present on a
> > tektite/impactite that resemble atmospheric
> effects,
> > should one use the term "pseudo-regmaglypts" or
> > "ventifacts"? Or should one go ahead and use the
> > same terminology used to describe these features
> in
> > meteorites? (orientation, flowlines, etc)
> >
> > 4) have impactites/tektites ever been studied
> in-depth
> > in the lab to determine their exact source? It
> seems
> > to me a minor mystery to solve. We can compare
> > chemistries of specimens to determine a lunar or
> > martian origin, but we lack the science to
> determine
> > where a tektite formed? I'm surprised this is
> still
> > a "controversial" issue - modern science has
> peeled
>
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Received on Sun 06 Apr 2008 12:40:23 AM PDT