[meteorite-list] Re: Stretch tektite

From: meteorites_at_space.com <meteorites_at_meteoritecentral.com>
Date: Thu Apr 22 09:43:29 2004
Message-ID: <20010709014736.3083.cpmta_at_c000.snv.cp.net>

On Sun, 08 July 2001, Michael Blood wrote:

> Hi Steve,
> I would LOVE to see a jpg of your stretch tektite - do you have one on
> a URL somewhere? Would you show us?
> Thanks, Michael

Michael, and list members.

Here is the post that started the "Futrell vs. Schoner tektite debate"

Click on the photo links to see what this specimen looks like.

A Most Unusual Tektite From Thailand.  
This is the most amazing "stretch" tektite that I have ever seen, and shows the feature better than most of the so-called "elbows" that have been found.  I obtained it in a batch of tektites at the recent Tucson Gem and Mineral Show, and though I did not see any others like it, and there were thousands of tektites to go through, I think that they are more common than most people think.
As can be clearly seen in the above picture, apparently it was a dumbbell form that in its molten state stretched and lost its other half.  The first photo shows the splayed edge to the left.  The bright area on the left edge, and almost in the center of that edge is a "web" effect, like the web of skin between the fingers where the original semi-solid surface spread.  This stretch area is very similar to the web sometimes found in the more common "elbow stretch" tektites.  But in the above specimen, the entire left surface is smooth and clearly shows stretching, whereas the original surface not stretched is a typical tektite surface.
The side shown in the next photo( http://www.geocities.com/american_meteorite_survey/stretch2.jpg )clearly reveals the stretched surface.  Glossy and smooth, and looking like taffy (to the left) it contrasts sharply with the original surface of the dumbbell.
In the next four photos the green element of this amazing tektite has been accentuated so as to reveal the stretched areas more clearly. 
In comparing examples of known elbow tektites and this one, it is possible that these forms may not be so much the result of spinning.  But instead the elbow form might be caused by atmospheric pressure against a dumbbell or elongated mass that orients in the atmosphere after cooling in a vacuum.  The bend is caused when the semi-solid oriented mass then gives at the weakest point. In the above example it gave away completely, and afterwards the two pieces spun away in line of the break further stretching the glass. 
With respect to thin elongated masses that orient against atmospheric pressure, I encountered one Glorieta meteorite of about 41 grams that was bent into a horseshoe shape by atmospheric pressure. The sharpest point of the bend revealed stretching and cracks in the metal.  (Mike Farmer now owns this very unusual and unique Glorieta specimen. Of all the specimens I recovered in almost 18 years only one such piece was found.)   
Though the material of the Glorieta meteorite is iron, and the tektite having been semi-molten glass the physical process that bent them is the same.
If tektites oriented against the air stream in a semi-molten state the effect would be a bend with a taffy like stretch area, or if completely separated, like the specimen shown in the above photos. 
This and other examples of "stretch" tektites are a clear indication of their terrestrial origin, and for two reasons.  The first being that they would have cooled long before they entered the Earth's atmosphere, and there is little if any chance that such forms could have survived had they been formed on the moon, ejected, then later entered the Earth's atmosphere at 7+ miles per/sec.
(This is the minimum free fall velocity that an object falling from the distance of the moon would achieve after being thrown from the surface of the moon) 
With regards to flanged buttons, there is no doubt that they entered the earth's atmosphere at hypersonic speeds.  In the 1950's this was proven when spherical tektite type glasses were exposed to the hypersonic exhaust of rocket engines, and the result were "flanged buttons."  Though this was proof of their hypersonic flight through the Earth’s atmosphere it did not prove that they were blasted off of the moon.  With recent evidence the consensus is that flanged buttons were spherical tektites that were ejected from the surface of the Earth in an impact event and thrown to very high altitudes, then cooled and sometime after re-entered the Earth's atmosphere at hypersonic speeds. 
It is generally accepted that the Australites and Indochinites were formed at the same time.  And though flanged buttons clearly indicate that they encountered the Earth's atmosphere at hypersonic speed, the very rare "stretch" tektites found closer to the suspected imactor site reveal that some of the glass never achieved velocities sufficiently high enough to cause ablation of their surface features.
This fact alone implies a terrestrial origin, for had they all come from the moon, then the minimum speed of entry into the earth's atmosphere,( 7 mi per/sec) would have most certainly have obliterated "stretch" forms, and flanged buttons and flanged dumbbells would be the rule rather than the exception.  Stretch forms also demonstrate that the peculiar lined and pitted surface features of tektites are caused at the time of their formation and are not the result of soil acids etching the glass over the long period of time that they were in the soil.
Steve Schoner,
American Meteorite Survey 
P.O. Box 1003
Flagstaff, Arizona  86001
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Received on Sun 08 Jul 2001 09:47:36 PM PDT

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