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MeteoritesTektites with Brown
25th Aug 2009 01:50 UTCGordon c De'young
25th Aug 2009 04:06 UTCByron Thomas
Sorry
Byron
25th Aug 2009 11:23 UTCPavel Kartashov Manager
So you need in precise water content determinations in your glasses.
Besides that, finding of such phases as moissannite or native metals (Si, Fe, Ni etc.) in heavy concentrates from your glass may to confirm its tektitic nature.
By the way, I never saw "obsidian bombs". From other hand, these objects are similar to some indochinite specimens.
Kind regards,
Pavel
25th Aug 2009 13:36 UTCAlfredo Petrov Manager
25th Aug 2009 14:04 UTCPavel Kartashov Manager
In any case water content determination isn't hard accessible and expensive test. Oregon isn't Upper Volta. ;)
25th Aug 2009 15:10 UTCSteven Kuitems Expert
25th Aug 2009 15:31 UTCPavel Kartashov Manager
If this material really contain tektite particles, only two from the picture are similar to tektites (yellow arrowed).
From my point of view, it is enough to break such "tektite" and obvious obsidian specimens and compare outer view of broken surfaces of both. If they are the same, all material is obsidian.
25th Aug 2009 16:07 UTCByron Thomas
Byron
25th Aug 2009 16:08 UTCMike Jensen
It is almost certainly obsidian. Here is a photo that shows obsidian with cristobalite from California;
http://www.mindat.org/photo-5103.html
Notice how the crystals are radiating spheroids in both photos.
If you need more here is a great test that most of us non scientist types can preform;
from O'Keefe, John A 1976 Tektites and Their Origins
A tektite is a natural glass, usually black, but sometimes green, brown or gray, which occurs in lumps, usually a few centimeters in length, having no chemical relation to the local bed rock. Tektites are broadly similar to some terrestrial volcanic glasses (obsidians); they can be distinguished by heating to the melting point with a blowpipe or a blowtorch. Obsidians turn to a foamy glass, while tektites produce a few bubbles at most, because of their much lower content of water and other volatiles. Under the microscope, obsidians are seen to have abundant microlites (microscopic crystals); tektites have essentially none.
Here is a excellent article that shows pictures of the results of the blowtorch test;
http://www.meteorite-times.com/Back_Links/2003/January/Jims_Fragments.htm
I actually get that same question several times a year. Unfortunately in almost 15 years I have never had any pass the test.
Good luck with your test.
Mike Jensen
25th Aug 2009 17:41 UTCPavel Kartashov Manager
take 1 g of tested specimen crushed in powder and heat it up to 1000o C in furnace. After cooling weigh it. If you have obsidian, it will give 900 mg or less. If you have tektite - its weight still stay around 1 g.
Really it is hard busines to look for tektites along Western coast, too much obsidian spread in this region.
25th Aug 2009 19:03 UTCAdam Kelly
Can't wait to see what the results of the tests are!
25th Aug 2009 19:26 UTCAlfredo Petrov Manager
25th Aug 2009 20:32 UTCKen Doxsee
26th Aug 2009 01:05 UTCGordon c De'young
26th Aug 2009 02:14 UTCAlfredo Petrov Manager
Please, Gordon, forget about museum opinions; just do the necessary tests yourself - It isn't difficult.
26th Aug 2009 12:45 UTCJolyon Ralph Founder
Sadly it IS very difficult to do a test, however simple, that could turn your valuable tektites into worthless obsidian.
Such is human nature.
26th Aug 2009 16:10 UTCGordon c De'young
26th Aug 2009 18:00 UTCAlfredo Petrov Manager
27th Aug 2009 00:48 UTCGordon c De'young
27th Aug 2009 02:16 UTCAlfredo Petrov Manager
Warning: Testing stuff becomes addictive! Have fun.
Alfredo
27th Aug 2009 16:54 UTCGordon c De'young
27th Aug 2009 18:02 UTCMark Gottlieb
Please keep us posted as your inquiry into these objects progresses; this has been an interesting thread to follow. Personally, I am betting on "not tektites", although I have seen a bunch of similar looking objects offered for sale as tektites.
You may want to check up on some of the Mindat posters - these folks really know what they are talking about and are the "experts". Just so you know, there are some big time museum professionals lurking in the background on Mindat. Perhaps some of them will chime in on the debate.
Mark
27th Aug 2009 19:51 UTCLachrisha Smith
28th Aug 2009 18:30 UTCGordon c De'young
2nd Sep 2009 04:48 UTCGordon c De'young
I finally got a chance to take a closer look at the “tektites”.
I am still somewhat caught on a definitive answer.
On the plus side:
They are the correct color, overall shape, the are definitely glass, correct size range, and some have surface features similar to tektites.
On the negative side:
I broke a real tektite from the Australasian fall for comparison. It was difficult to break the Australasian tektite; it took several tries. Your tektite broke much easier. However, both appeared to be a shiny black glass. Breaking easier makes me suspect that your tektite might have a higher water content. Real tektites have an extremely low water content, while obsidians have a fairly high water content.
Next, your tektite on a thin edge of broken glass has a light gray color with just the very slightest tint of green. The reason that green is so important is that at the high temperatures at which tektites are created, oxygen is driven out and the iron present is all converted to ferrous iron, giving the tektite a strong green color. The moldavites are all an intense green. The Australasian tektites are a dark brown with a green tint; their color comes from the ferrous green plus a reddish color from submicroscopic spherules of iron that were injected into the glass when the meteorite struck the ground. Your tektite only has a bare hint of green; it resembles some obsidians. There is a hint of some layering or color variation in you tektite. I lack a gem cutter’s diamond saw to make a thin slice of the tektite to examine it thoroughly.
The avocado surface texture is different than the surface of any tektite that I have ever observed. On the other hand, some of your tektites do have surfaces very similar to those found on real tektites.
I am still caught between the two possible origins: tektites versus volcanic glass. The main feature that will determine the answer is the water content of the glass. I checked on the Internet and I have the names and address of some geologists who might be interested and who can perform the necessary tests. If you want to, you can mention my name and title as referring you to them.
S.S. Hughes, J.W. Delano, and R.A. Schmidt
Department of Chemistry and Geology
Oregon State University
Corvallis, OR 97331
I hope this helps a bit. I would love for these stones to be real tektites, because it would represent a new fall.
But I am cautious because of the large amounts of obsidian that have erupted in the Oregon area.
Sincerely,
Roger Weller
16th Oct 2010 01:24 UTCAnonymous User
Most of the above varieties have been analyzed and they are obsidian. Healdsburg glass is the most troublesome one to place- like a tektite it is quite dry, has a very high fusion temp and some reduced-phase iron; but abundant microliths would be hard to explain in a tektite and Healdsburg is full of them.
I have found over 750 bediasites and one georgite and collected some obsidian(?) specimens near Healdsburg. I collect tektite analogs and I am always open to adding more specimens from different locations.
Should you recover specimens that are teardrop or dumbell shaped and they are glass then you can get excited- the likelihood of being a tektite would be very great!
Happy hunting,
Briman
11th Jan 2011 20:24 UTCBri Dragonne
The brown one is certainly Obsidian of the variety (Or market name...) Mahogany Obsidian.
The gray spheres inside are certainly Cristobalite.
That being said, it is highly improbable that a few tectites managed to randomly fall in the same area as the other, certainly Obsidian pieces.
It would be like finding a random plastic apple at the bottom of an apple tree, mixed with the natural apples already on the ground, I should imagine ;)
-Bri
7th Feb 2011 16:38 UTCKarie
31st May 2013 22:08 UTCAlicia
My only one question is could the fact that 2.8 billion years ago and the increasingly tectonic activity possibly alter the chemistry of the tektite through pressure and or cooking. In the same area I found a great number of wonderful samples of quartzite in the strong calcite and potassium coloring. However I am a student and may be over my head on this, but I'd still like to see the outcome and others thoughts, provided this string is still attached to known emails.
6th Dec 2015 06:08 UTCRobert Verish
Through the use of an XRF unit, I have found a method to quickly distinguish between obsidian and tektites.
My interest in this subject began when I recently found a rare variety of greenish-yellow/brown obsidian. (see photo)
I am aware of all the published obsidian source locations close to my find locality, but none of them seem to
properly match my obsidian. I realize that paleo-trade-routes involving obsidian can cover great distances.
So, obviously I'm still looking for the source of this obsidian.
In the meanwhile, I've started to write a paper about a new technique to test between obsidian and tektites.
When it is finally published, I will add a link to it, here.
12th Feb 2016 12:56 UTCReiner Mielke Expert
Looking forward to the results as I am sure a lot of other people are as well.
19th Sep 2016 06:15 UTCSandra Briggs
19th Sep 2016 08:13 UTCRobert Verish
Tektite experts have told me that if my natural glass specimens are "very magnetic", I can forget about it being a tektite.
On the other hand, I have tested impact-glass from various craters and some of them are attracted to a magnet.
Coincidently, I just posted an article on this subject where I presented the preliminary test results of 60 specimens
that I tested with a handheld "XRF". Here are the links:
http://www.meteorite-times.com/bobs-findings/part-2-tektite-or-impactite-or-obsidian-pseudo-tektite/
and my blog with updates:
http://meteorite-recovery.tripod.com/2016/sep16.htm
23rd Sep 2016 09:49 UTCRobert Verish
My name is Robert Verish, and I made a post/reply to this thread "Tektites with Brown" (color).
Here is the link to my previous post:
http://www.mindat.org/forum.php?read,98,149850,393711#msg-393711
You are also one of the several people that have replied to this thread, and you also requested to be given "updates" if there was any new information. If you are no longer subscribed to this thread, you may not be getting "updated".
I have not received any replies to my latest post (Sept 2016), so I have decided to reply directly to you, and your earlier request.
In my last post, I was trying to explain that, while I was conducting tests on specimens of tektites and obsidian, I have stumbled across a "simple" test method that (so far) has consistently been able to "quickly" distinguish between volcanic-glass (obsidian, i.e. marenkites) and impact-glass (especially, tektites) . I was using a handheld Niton XRF for this testing. Although getting access and using an XRF may not be considered "simple", getting test results was certainly "quick". With only a minute of X-ray irradiation, test results are immediately displayed on a screen.
I recently published an article on this process where I presented the preliminary test results of 60 specimens of obsidian and tektites that I tested with this handheld "XRF". To see these results, here are the links:
http://www.meteorite-times.com/bobs-findings/part-2-tektite-or-impactite-or-obsidian-pseudo-tektite/
and my blog with updates:
http://meteorite-recovery.tripod.com/2016/sep16.htm
This testing is still on-going, so contact me via personal message, if you have a potential tektite specimen, or have an unusual greenish/brown obsidian that you would like to have tested.
23rd Oct 2016 03:03 UTCRusty Shackleford
19th Jun 2017 22:12 UTCRobert Verish
I just now came across your question. The blunt answer is, "No!"
Every "Healdsburgite" that has been donated to me, all of them have failed both my XRF testing and the "flame-test". These results were reported in my "Bob's Findings" article that preceded the "Part 2" article that I mentioned above in my September 23, 2016 post. I won't rehash the details, but here is more information, at this link:
https://www.meteorite-times.com/bobs-findings/tektite-or-pseudo-tektite/
The above article reiterated the need for a cheap, simpler (and non-destructive) test to replace the old-school "flame-test" which was fraught with too many false-positive results (actually, insufficiently heated specimens).
I found that the hand-held Niton XRF devices to fit those requirements, except for "cheap" (unless you can beg, borrow, or steal free test-time on a friends XRF).
In any case, among the many dozens of tested specimens of obsidian and tektites, I have yet to find any overlap in the values I obtained with my XRF for Ti (titanium). All of my tektite specimens gave values higher than any of my obsidian samples. Testing is still on-going.
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