[JimBob]

The map below is from the web site I got all the information from and linked to in my last post.

Note all of the impacts that are recorded in the literature compiled by Steven Dutch.


from http://www.uwgb.edu/dutchs/planets/impact1.htm


As I have stated above, this is a tektite formed from ejecta from an impact site. Impact crates can be found all over the place.

Dr. Dutch writes on the page linked above:

"If you didn't know better, you'd suspect meteors were targeting Australia, North America and Europe. It's not that there are so many craters there, it's that there are so many geologists there, plus countries affluent enough to do detailed geologic mapping. A complete map would have the whole earth covered to the same density. To show you how hard it can be, the Chesapeake Bay impact structure, on the doorstep of Washington D.C., was not discovered until the 1990's, because it is completely buried."

The facts that there are impact sites all over the place in the "states" of Northern Territory and Western Australia just makes it's existence near Lake Argyle very explainable.

Oh - do they sell make and socks at Lake Argyle?

[RD]

The flanged button tektites have concentric features, but are not cupped like Bailey's find, (so I'm still not a believer).

 [ Invalid Attachment ]
http://www.tektitesource.com/

Having read a bit more I'd up my previous valuation if it is a tektite,
[but that's of no interest to Bailey who is "not remotely interested in its retail value".]

Tektite Tests you can do at home ...

2) The Magnet test: Only crystalline substances show significant magnetic properties, and tektites have essentially no crystals. Further, oxygen is one of the volatiles that partitions out of the liquid glass phase in the extreme conditions of tektite formation; Hence, available iron occurs in a highly reduced state, literally dissolved in the glass. In terrestrial obsidian, iron often occurs as crystalline magnetite, an oxide.

Using fairly sophisticated equipment, I have verified that tektites have magnetic susceptibilities that are often an order of magnitude or more lower than terrestrial glasses. This difference is sufficiently large that it can be detected with a strong magnet.

Hang a good Neodymium-Samarium magnet on a thread, then pass your suspect material close by. If there is any visible deflection of the magnet pendulum, it is not a tektite. This is conclusive. If nothing happens, the test is inconclusive, but permissive. There is reason to expect that all tektites will be non-magnetic, but not all non-magnetic materials are tektites.

What if Fe-Ni sphereoids are present? I'm not absolutely certain, but suspect that their concentration is virtually always too low to detect magnetically.


3) Transmitted light color Test: A meteorite list respondent passed along word that the late, great tektite enthusiast, Darryl Futrell, used transmitted light color as a screening criterion. While many tektites appear opaque black in reflected light, all will transmit light along thin edges with strong backlighting. Check the color.

Australasian , Ivory Coast, Tibetan, and Bediasite tektites are a molasses-brown with greenish tinges...

http://www.tektitesource.com/Tektite_tests.html

Another tektite test you can do at home ... http://www.tektitesource.com/Tektite%20Specific%20Gravity.htm

[JimBob]

... a former professor (and a personal hero of mine) wrote an article of ejecta from impact craters


Terrestrial implication of layering, bubble shape and minerals along faults in tektite origin
Virgil E. Barnes
Bureau of Economic Geology, The University of Texas, Austin USA
Received 4 February 1964.
Geochem. Acta

Abstract
Both detrital mineral grains and minerals which crystallized in situ were first found in tektites along faults in Muong Nong-type indochinites from Kan Luang Dong, Thailand. The detrital mineral grains have the optical properties of quartz and are within the size range of quartz abundant in local soil and rock. Such a correspondence in grain size strongly implies that the tektites from Kan Luang Dong are locally derived. Layered tektites are probably the result of the accumulation in puddles of melt from flash fusion of bare patches of soil and rock. The faulting took place while the melt was very hot and the evidence for this is: (1) perfect welding of the fault-fractures with detrital grains equally embedded in the glass on either side of the welds, (2) growth of minerals along the faults, and (3) warping of the fault planes by movement of the melt following faulting.


It is my hypothesis that this is ejecta from an impact site that did not get totally melted, but only mostly melted. This piece is a bit of country rock (surface rock) ejected from the crater that is mostly glass but still retains characteristic of the original rock.

The button is formed (I am finally answering your question) in the same way as the buttons in the bottom part of the black and white picture above - by aerodynamic shaping of the partially melted rock entering the atmosphere. The pits all over it are places where material has ablated from the rock while it was reentering the atmosphere.

The fact that it is so hard, heavy and has aerodynamic shape TO ME indicate only an origin formed in the atmosphere.

I have no argument with the data in the last post. It is how rock collectors define tektites. But it is a popular misconception that ALL tektites are like those you referenced.

The ablation pits on both the rock pictured in the last post and the rock Bailey posted are a dead give-away that these two rocks had the same origin.

"Sometimes the boundaries between tektite and impactite become blurred. A tektite is effectively the material thrown away from the impact site, with impactites actually being at, or close to, the impact site. There is no set distance from a crater that an object must be before it crosses over from impactite to tektite. Notably, true tektites are not usually found close to the source crater. The decision to call an object a tektite or impactite is largely a personal choice. My favoured means of differentiation is that a tektite should show a degree shape formation (which may, or may not be, secondarily altered by atmospheric re-entry or impact with the ground). I consider amorphous rocks to be impactites. As such Moung Nong tektites could be considered impactites (even though, prior to landing they may have had a shape - this is a grey area). Spheres, dumbells, tear drops, etc. are 'true' tektites."

AND

"Are tektites a kind of meteorite?

No, tektites are formed by large meteorites or asteroids/comets impacting the Earth, but they are principally composed of melted terrestrial (Earth) rock. Traces of the extraterrestrial component may be found by detailed isotopic analyses. Meteorites come from space, tektites come from the Earth."

Both from http://www.tektites.co.uk/

The owner of this site is a geologist


The rock Baily has posted it a dumbbell shaped tektite with a button on it.

[RD]

The rock Baily has posted it a dumbbell shaped tektite with a button on it.

Bailey's button is an innie , button flanged tektites have an outie ...

 [ Invalid Attachment ]
http://www.tektitesource.com/

[geo driver]

from a stupid point a view, you ever seen a water droplet landing on the surface of water?  the plop goes down then up, or drop a stone in wet cement see what happens, if its what JB sais it is this could explain the innie, the rim of the stone looks as if its been placed ontop of the rest, like one part had cooled and semi hardened earler then the rest

[LeeE]

I couldn't help notice that the map that JimBob posted includes at least one unverified impact crater i.e. Silverpit, the origin of which, I believe is still hotly debated and unproven.  It also doesn't include the Ullapool impact, which I believe has been established pretty clearly by the presence of shocked quartz, Iridium traces and an ejecta field.  The evidence for the Ullapool impact was published in March 2008.

Also not shown on that map is the suspected impact in the Congo, which was recently discussed in this thread:

http://www.thenakedscientists.com/forum/index.php?topic=28585.0

but then the origin of that crater is still to be proved/disproved (just like Silverpit) and it has only much more recently been investigated too, whereas Silverpit has been known about for many years now, so its omission is more understandable.

Please don't get me wrong: I'm not trying to rubbish that map, as I'm sure it's going to be mostly correct, but just point out that it can't be regarded as authoritative.

[JimBob]

EATING CROW



On second thought …

“Tektite” may not be the best label for this rock. First I asked the geologist who has the site http://www.tektites.co.uk/ -whom I post in my last post -.his opinion about this rock. Here is what he said.

“I believe you are referring to the dog deposit-like rock. This is certainly, 100% definitely, not a tektite.”  He went on to say it was not impact related and that is was “would say that this rock is well and truly grounded. A terrestrial rock of some description.” I do not totally agree with the second statement. It is not totally of terrestrial origin but also shows some shaping in the atmospher - the button bailey refers to.

OK It is of terrestrial origin. This is what I have been contending.

Yesterday I went to the Texas Memorial Museum yesterday to see if I could find what I rememberd seeing among the bediasites and related material Dr. Barnes had collected. It was among his material where I has seen something similar rocks when I was in school (Medieval times). What I found were some examples of impact ejecta fallback breccias. Although these didn’t have the limonite coating (the thing that makes the rock waxy) these specimens were remarkably similar to the picture Baily posted.   

And I found a picture online of a fallback breccia from Wisconsin, USA


from http://www.fossilmuseum.net/Fossil_Galleries/Stromatolites/DS612/Stromatolites61.htm

This is a stromatolite with trapped quartz grains and is from material ejected from a impact crater.


An “impact ejecta fallback breccia” is what I described in my post of  March 16, 2010:

It is my hypothesis that this is ejecta from an impact site that did not get totally melted, but only mostly melted. This piece is a bit of country rock (surface rock) ejected from the crater that is mostly glass but still retains characteristic of the original rock.

The button is formed ... in the same way as the buttons in the bottom part of the black and white picture above - by aerodynamic shaping of the partially melted rock entering the atmosphere. The pits all over it are places where material has ablated from the rock while it was reentering the atmosphere.

The fact that it is so hard, heavy and has aerodynamic shape TO ME indicate only an origin formed in the atmosphere.

There is really no time to eat crow. But properly prepared it taste like chicken.


Bailey's Rock - an Impact Ejecta Fallback Breccia"

[Bailey (OP)]

thanks again for your interest jb,i would still like to send it to you,ill contact relevant people and see what i can do about giving you a closer look..even though ive had this for years i still stare at it and wonder how the hell it was formed.

[RD]

i would still like to send it to you

This may be relevant ...

IMPORTANT NOTICE TO AUSTRALIAN RESIDENTS:

It is illegal to send meteorites overseas that have been found in Australia. Doing so breaks Federal Law under the 'Protection of Movable Cultural Heritage Act (1986)' and can incur heavy penalties including fines and/or a prison sentence. Special export permits or clearance letters must be obtained to send any Australian meteorite overseas which on occasion can be denied, reflecting the serious intent of the legislation.

http://www.meteorites.com.au/found.html