[meteorite-list] Holbrook Tektites ( HEAT TESTING of TEKTITES)

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Fri, 27 Aug 2010 23:05:13 -0500
Message-ID: <0CF549236393499FA77B0C5D1086594B_at_ATARIENGINE2>

Brian, Tom, List,

Libyan Desert glass is 98% pure silica, the
purest naturally discovered glass on Earth.
http://www.pisces-press.com/C-Nav/ldg.htm

While one sees as examples are clear, gem-like
LDG, many of the fragments found on the ground
(and tossed aside as "dirty" or not pretty enough)
are tabular and layered, clean, dirty, clean, dirty,
like the Muong-Nong tektites found in Laos
and Thailand.

Boslough at Sandia has a airburst theory...
naturally:
http://www.sandia.gov/news/publications/technology/2006/0804/glass.html

Most people think an impact origin. Too many
references to cite.

There are some completely dopey theories about
LDG, too. I found this one to be worth a good laugh:
http://www.b14643.de/Sahara/LDG/index.htm

And there are some people still think tektites
are volcanic:
http://www.rasc.ca/journal/pdfs/2004-10.pdf

Analysis of LDG can be found in Christian Koeberl,
"A Meteorite Component in LDG". He finds excess
cobalt, nickel, iridium:
http://www.lpi.usra.edu/meetings/metsoc2000/pdf/5253.pdf

Here's the actual earlier work by Koeberl, the full
paper, with complete data:
http://www.univie.ac.at/geochemistry/koeberl/publikation_list/132-Libyan-Desert-Glass-Proc-Bologna-Mtg-1997.pdf

Anyone have an idea why there's a ten-fold excess
of uranium in LDG? I'm sure that's spawned a few
whacko websites!

I quote from Koeberl "...none of the sands or sandstones
...are good candidates to be the sole precursors of LDG."
Formation temperature has to be high enough to melt
zircons, as they contain melted zircons (as many tektites
do). Ever tried to melt a natural zircon?

What is often missing from the discussions of the origins
of the LDG is the fact that the Libyian-Egyptian Desert pf
28.5 million years ago was NOT a desert. It was swamps,
vast lakes, bogs, and snaking bayous. What was not open
water was wet and very densely forested between 24 and
32 million years ago. The "Sahara" to the west and south
was grasslands and scattered forest.

Yeah, I know. Doesn't look it, does it? But in the Oligocene
Epoch it was more like the Amazon Basin on a smaller,
dryer scale. It's a rich source (only source, actually) of fossils
of early primate ancestors of apes and men. It seems to be
where we learned to hang out in trees (literally), the black
anaerobic crap underneath being something you didn't
want to fall into.

These wet basins were filled with hundreds of feet of
sand blown in from the west as the Sahara began to dry
out. This is the target geography that an impactor would
have struck. The high silica content pretty much has to
mean that LDG was made entirely from sand. The fact
that LDG is not as "dry" as most tektites may come from
the fact that the target soils were underwater some depth.

Merely geusses, though.


> Is there a good book on tektites?

No. The study of tektites drives people crazy, and
crazy people do not write good books...

O'Keefe's 1976 "Tektites and Their Origins" book was
posted online for years but it's gone now. You can get
a copy on Amazon for $200. (O'Keefe was the "O" of the
"YORP Effect" or Yarkovsky-O'Keefe-Radzievskii-Paddock
Effect). Other books by Heinan and Provenmire are hard
to find. Now that I think of it... All books on tektites are
hard to find


Sterling K. Webb
-----------------------------------------------------------------------------
----- Original Message -----
From: <Starsinthedirt at aol.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Friday, August 27, 2010 10:20 AM
Subject: Re: [meteorite-list] Holbrook Tektites ( HEAT TESTING of
TEKTITES)


> Very well done Brian! Thanks for sharing your results.
>
> Your experience with the LDG, " Libyan Desert Glass - we took it up
> to
> 1,815 Centigrade / 3,300
> Degrees Fahrenheit and it was tacky on the surface , BUT did not
> Melt"
>
> This made me wonder again what others think of the idea that LDG is a
> glass
> meteorite and not a glass created in the same manor as most tektites.
> This is not original thinking on my part as I have heard it proposed
> as one of
> the theories on LDG.
>
> Any thought on this?
>
> Some samples of LDG are shaped more like a meteorite than a tektite
> aside
> from the fact that they are glass!
>
> Tom
> In a message dated 8/27/2010 3:24:13 A.M. Mountain Daylight Time,
> brian at aajewel.com writes:
> Greetings to Dennis, Mark and List Members
> HEAT TESTING OF TEKTITE
> Aubrey has some good & interesting observations concerning Testing
> Tektites on his sight
> http://www.tektites.co.uk/tektite-tests.html
>
> Personally , I have access to professional Glass Blowers with tons of
> experience.. They work with Common , Borosilicate ( Pyrex ) and
> Dichroic Glasses.
> All types of Glass have different melting temperatures , and working
> together with the Top Production planner ( Brent ) who is versed in
> Heats and Flames required for melting these various types of glass,
> we set about to Heat Test Several Types of Tektite. Temperature is
> KEY to observations. Brent was aware of our goals and took time to
> test various temperatures as well as using test pieces and had far
> more information than I am able to convey simply. Lets just say that
> Coefficient of Expansion, Coloration and other physical properties
> were also in question during our tests.
>
> Glass melts at a relatively LOW Temperature, about 485 Centigrade
> / 900 Degrees Fahrenheit ( Varies with the amount and types of
> Alloys in the glass )
>
> Bolorsilicate ( Pyrex ) at about 820 Centigrade / 1,510 Degrees
> Fahrenheit
> Thailandites, Philippinite , Moldavite and Quartz Glass melt at
> about 1,665 Centigrade / 3,029 Degrees Fahrenheit
>
> Libyan Desert Glass - we took it up to 1,815 Centigrade / 3,300
> Degrees Fahrenheit and it was tacky on the surface , BUT did not
> Melt, as my friend stated "it is laughing at us"... We are still
> looking for a hotter Hydrogen Flame Unit to see what the actual
> melting point is.
>
> Darwin Glass - I have yet to test it, I forgot to bring samples.
> Maybe
> soon...
> Obsidian explodes when heated quickly.
>
> SO - it is easy to eliminate an Obsidian as a Tektite , just by
> throwing alot of heat at it quickly.
> Glass and Borosilicate varies from Tektites , easily, by applying
> heat to samples of each set side by side, see what melts first ..
> Don't worry about destroying the Tektite , it will be safe since the
> glass will melt much sooner than any tektite, and if the Tektite
> melts at the same temperature as Glass ?? It was not a Tektite.
> Quartz Glass is rare and to find a piece while looking for Tektites
> is just to unlikely to ever happen.
>
> The reason Tektites can withstand such High Heat is that the
> impurities that allow Glass to melt at lower temperatures have been
> Burnt out of them already.
> MY THEORY:
> Thailandites, Philippinite and Darwin Glass have coloration from the
> residue left by these Burnt off elements. Heavily contaminated.
> Moldavite also gets its coloration from the Burnt off elements. Less
> Contamination
> Libyan Desert Glass is very clean and was intensely heated to remove
> even the residual left by burning off impurities. Minimal
> Contamination.
>
> Highest Regards to All
> Brian S. IMCA # 7381
> http://stores.ebay.ca/AAJEWELCOM
>
>
>
>>------------------------------
>>
>>Date: Thu, 26 Aug 2010 13:15:36 -0400
>>From: <cdtucson at cox.net>
>>Subject: Re: [meteorite-list] Holbrook Tektites ( Magnet canes are
>>evil)
>>To: meteorite-list at meteoritecentral.com, Dennis Miller
>><astroroks at hotmail.com>, Mark Bowling <minador at yahoo.com>
>>
>>Dennis, Mark,List,
>>Interesting you mention finding rocks that resemble certain
>>tektites. You describe them as looking translucent and weathered
>>with a tektite texture.
>>Years ago I found what I thought was a strewnfield of tektites in
>>Southern AZ.
>>They too looked like what you found.
>>I took them to ASU and Dr. Moore had his assistant attempt to melt
>>one of them.
>>He explained that a true tektite would simply melt like glass
>>similar to the way a glass blower melts glass.
>>If however it gets frothy and white it is not a tektite but likely
>>natural obsidian glass. This had something to do with the amount of
>>water. Apparently tektites are much dryer than obsidian.
>>Well, they tested frothy and therefore deemed to be sand blasted
>>obsidian. I believe he also said they are not magnetic. Some of mine
>>were magnetic others were not.
>>Curiously, I have since found that Surf-tumbled Sea glass has
>>exactly the same appearance as these sand blasted obsidian orbs I
>>found in the desert. The only difference is that sea glass does melt
>>like tektites so, the melting test does not work on them.
>>In fact other than the flanged buttons, to me many of the "Tektites"
>>look more like Sea-glass than anything else.
>>If you are unaware of it. Sea glass is largely a product of surf
>>tumbled glass that has been littered or discarded by human activity
>>in the past.
>>If you Google it there are lots of people selling it.
>>What I found looks like either Columbianite or Georgia Tektite. two
>>different looking types all in the same find area.
>>Really Makes me wonder about the true origin of Tektites.
>>Carl
>>--
>>Carl or Debbie Esparza
>>Meteoritemax
>>
>>
>>---- Mark Bowling <minador at yahoo.com> wrote:
>> > Dennis,
>> > I have found?tiny glass spherules in some areas along the tracks -
> lots of
>> > them.? I think it's welding slag from RR operations.? I was
>> pretty excited until
>> > someone suggested it (I never had them tested, but?hard to
>> believe folks would
>> > overlook something significant until me...).?
>> > Nothing as big as you mention (other than the marbles we
>> > occasionally
>> > find).???In other places I?have found weathered obsidian which
>> > often
> has a
>> > tektite texture (though not the same).? I think it's caused by
>> > solution
>> > weathering.
>> > I have a magnet cane, but I never used it to pick up a
>> meteorite.? It's just a
>> > fashion statement I guess (peer pressure).? ;-)
>> >
>> > Mark B.
>> > Vail, AZ
>> >
>> > ----- Original Message ----
>> > From: Dennis Miller <astroroks at hotmail.com>
>> > To: meteorite-list at meteoritecentral.com
>> > Sent: Tue, August 24, 2010 3:08:13 PM
>> > Subject: [meteorite-list] FW: Magnet canes are evil
>> >
>> > > My modified ski pole (with Magnet) is more a walking stick and
>> snake flipper!
>> > > I have a question, Has anyone ever found small tektites around
>> the Holbrook?
>> > > I know if there were, that they were not the result of the
>> Holbrook splatter.
>> > > While there Sunday, I found what is either an egg shaped (5/8")
>> obsidian ball
>> > > or a tektite of sort. Light will pass through it but it has an
> unusual
>> > textured skin. I have seen a lot of Apache tears (obsidian orbs)
>> but none like this little guy.
>> > > Carrying a big stick at all times.
>> > > Dennis Miller
>> > >
>> > >
>> > > > Date: Tue, 24 Aug 2010 10:10:10 -0700
>> > > > From: ROBERT.D.MATSON at saic.com
>> > > > To: Meteorite-list at meteoritecentral.com
>> > > > Subject: [meteorite-list] Magnet canes are evil
>
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Received on Sat 28 Aug 2010 12:05:13 AM PDT