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MeteoritesTektite questions

10th Feb 2011 00:15 UTCJason Evans

Warning, may be to many questions for some people, just scroll down and if you see something you might be able to help with just comment on that! (also a small rant about metaphysical stuff)

Hi, I am primarily a mineral collector but have a small collection of meteorites and a few tektites, and I am awaiting my first sample of Libyan desert glass and i eventualy plan to add some other impactites like melt breccias, shattercones etc, I have a small bit of K-T boundary layer from colorado but dont know what to class that as, I'll call it a impactite!

Anyway I have some questions regarding Tektites, maybe i wont get an answer to all my questions becuase i think there is still much to learn about tektites, for instance therse seems to be no definate conclusion as to there origin, i'm still seeing some places saying they originate from the moon, and a lot of sites seem very reluctant to say they are definatley the result of a metor impact, most say thats the most probable cause but why is nobody prepred to step forward and say they ARE from a impact?

Can anyone suggest some serious reading about tekltites with scientificaly proven facts, that doesnt mention the word POWERFUL! I am getting really peed off with the new age crowd claiming that tektites (in particular Moldavites) have got intense powers etc, i dont feel any of these powers myself and i have 4 Moldavites, and one new age person said i had a strong aura so surely i should pick up on these powers! well i do not want this to be a dig at those folks so I shall say no more on that!

With a renewed interest in tektites afer my latest aquistion, which i would like to talk about in more detail later, i read about the Georgiaite group of tektites, something got my attention, i read on several sites that the Georgiaites are green, and i thought hang on, i thought only the Moldavites are green, so i looked for some images of Georgiaites and what did i find, yellow tektites, i found no pictures at all that showed a green tektite, they are certianly more yellowish in colopur than the black tektites but ive notice both my black tektites (unkown localitities) are yellowish with a strong light shone through them whereas some of the georgiaites did appear more yellow without needing a strong light source behind them but i didnt see any hint of green at all, does anyone have some photos of these "green" georgiates?

About tektite strewnfeilds, I shall use moldavite as an example, the moldavites are all found to the east of the crater which is beleived to be the source of the moldavites, (Nordlinger ries) I read somewhere a long time ago that whatever angle a meteorite strikes the earth it will always create a circular crater, my question is, why would the ejecta/moldavites only be thrown out to the east, surelly tektite strewn fields would form a circular ring around the source crater?

Tektite markings, until only a week or so ago i always beleived the markings were created by the molten material flowing across the surface as the tektite flew through the air, like the regmaglypts on meteorites but now i foudn out the markings are caused by acid eteching, how has this been confirmed? they really do look like flow markings to me, on my new moldavite which is a teardrop shape so it shows the direction of flight, the markings do seem to originate from the "nose" of the specimen and flow back across the surface to the tail, its quite cool really becuase they seem to whirl out like the arms of a spiral galaxy from a point on the blunt "nose" end of the moldavite.

Almost done now! just wondering if it is known what causes the green colour of Moldavites and why it is unique to moldavites

And finaly, I would like to show of my latest specimen, a 12.4 tear drop Moldavite (from a I.M.C.A member) so I am not asking if its the real thing or not! I just want to share it, with people who understand what it is and dont just say, oh it looks like a prune! becuase i think its the best Moldavite in the world! (i know its not really, I have seen better, but its the best piece i have seen that i am able to physicaly hold, would like to know what other meteorite/tektite fans think of it!

One photo is backlit using sunlight and one is not backlit, the backlit photo is the original pic, not the one i added to the mindat gallery becuase i painted the background white for that!

Hope someone can help answer some of my questions!

Jason

10th Feb 2011 02:06 UTCGerald Allen Peters

Jason,

From my library:

The softcover book, "Tektites, A Cosmic Enigma," by Hal (Harold) Povenmire (2003), 210 pages, is a scientific explaination without the new-age touch. Published by the Florida Fireball Network. Also by Povenmire is "Tektites -- A Cosmic Paradox (1997).

The hardcover book "Moldavites, The Czech Tektites," by Vladimir Bouska (1994), 69 pages. Published in English by Stylizace, Prague.

Both are good reading.

10th Feb 2011 09:04 UTCjacques jedwab

Several years ago, I explored the micromineralogy of tektites:

Jedwab, J.: Minerals deposited in tektite and impactite bubbles. Meteoritics, 1977, 12, 264-266.

The text is accessible through: http://adsabs.harvard.edu/abs/1977Metic..12..264J. Pictures are awful.

Very rewarding approach, but needs careful observations under RLM and analyses under SEM/EMP.

J.J.

10th Feb 2011 15:59 UTCAnonymous User

Jason:

All I can add is that color in the glasses are likely caused chiefly by iron. As in many minerals, different concentrations of iron and different oxidation states gives different colors and shades of color. Green, brown, yellow, and versions of these colors so dark as to become black are all possible. The fact that moldavites are typically green just speaks to typical iron content and oxidation state from that locality. I would expect a thorough examination of material from each locality to show a range of colors and saturations.

10th Feb 2011 18:31 UTCDavid Bruno

Hi Jason,

The reason they are found to the East of the impact site is because the meteorite came down in a West to East direction, this would scatter the vast bulk of the debris churned up by the event to the East as it mashed its way into the planet, just think of slapping the surface of water in a swimming pool, the vast bulk of the water you splash goes in the same direction as your hand is going prior to the impact. I suppose they could be thrown in a circle around the impact site but that would mean the meteorite would have had to hit the earth at an angle of pretty much 90 degrees to the horizontal plane, generally meteorites are pulled into the planet by the gravitational field as they are passing on their way, this causes them to land at an angle, think of throwing a ball to someone, it reaches the zenith of its trajectory then heads down at an angle to the horizontal as gravity pulls it back to earth, well it forms an arc but that doesnt matter in this case. Its all Newtonian physics stuff, conservation of momentum and that kind of thing.

db

10th Feb 2011 19:31 UTCJason Evans

So even though the crater may be round no matter on what angle the meteorite strikes, the ejecta is thrown out according to the angle of impact?

10th Feb 2011 21:50 UTCDavid Bruno

Thats right, though it is counter intuitive with respect the circular impact crater, I guess the only way I can think of an example is if you skim a stone on water it causes circular ripples but continues on in the direction you throw it. When I get a minute Ill see if I can find a better explanation.

10th Feb 2011 22:06 UTCDavid Bruno

impact craters

I found this it gives a good account of why impact craters are round.

11th Feb 2011 00:27 UTCVik Vanrusselt Expert

www.tektites.co.uk seems to be a good site about tektites and everything about them (I've used it before for an explanation about my 'thailandite' tektite). However, the site seems to be offline at the moment...

Vik

8th Oct 2011 16:54 UTCGabriella Paparella

Could the reason for the green color of moldavite be attributed to olivine-containing meteorites/asteroids? Does it contain olivine? I've read conflicting info. Here's a NASA artcile about an olivine-containing asteroid: http://science.nasa.gov/science-news/science-at-nasa/2010/30dec_samplereturn

22nd Nov 2011 22:07 UTCAlfredo Petrov Manager

Phanie, moldavites are mostly formed from melted sandstone, so there's lots of silica glass in them, but no olivine.

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