Stretch Tektites

Stretch tektites are tektites that had a brittle exterior and a molten interior. When the brittle skin split, the molten (honey-like) interior was exposed and stretched. To qualify as a stretch tektite clear angular distortion must be evident in the tektite. Starburst Rays or Starscars formed in an identical manner, but are not strictly termed 'stretch tektites' becuase they lack the angular distortion.

ABOVE: Figures from the classic Nininger and Huss, 1967 paper.

The closer the impact site the more common these features are. They have previously only been convincingly recorded in Indochinites. Norm Lehman also has a fairly convincing moldavite (also a proximal splashform type) - check out his website http://www.tektitesource.com/taffy_cored_tektites.html. Theoretically stretch tektites should also be found in proximal Georgiaites and proximal Ivorites (which are also splashform), but these tektites are very rare and so not surprisingly this morphology has not been found in these two groups of proximal tektite.

ABOVE: My Stretch Indochinites. Nice, but not as nice as those in Nininger and Huss, 1967. Scale cube is 1 cm and relates to image on the left.

                 

ABOVE: (in colour) Four stretch tektites from the collection of Guido von Berg. Thanks for these great images!

 

On this page, for the first time, I present two probable stretch Philippinites. This goes totally against my thinking and is hard to explain initially. I have no doubt that Philippinites re-entered as solid bodies, yet I have two possible stretch tektites and two to three 'sagged' teardrops. These are 100% definite Philippinites from Paracale and result from searching 200 kilos (so far) of Philippinites and a brief search of an additional 150 (?) kilos. I'm still cataloging the rest of these.

ABOVE: Two Philippinites. The one on the left is 66.1g and came from Des Leong. He said he had a stretch tektite and I said 'no it can't be as Philippinites were solid during re-entry with no molten core', so he gave it to me with some other stuff I purchased from him. Up until today I put it down as a curio and nothing more. Then I found the one on the right today 8th September 2009 in a pile of tektites I left in a bag for the last 8 months. The one on the right weighs 32.2g.  Both specimens have two ends with circular bubbles and then a sandwiched stretched area in the middle with stretched elongate bubbles - in the photos this is more evident on the bigger 66.1g specimen, but the 32.2g has the same stretched bubbles in the central area (photo not as good as real life). Next is the angular distortion as the two solid end parts seperated from one another leaving the molten stretched middle part. The rotational effect is very evident in the smaller 32.2 g specimen (see the middle and bottom photo) and this was key to recognising this for what it is. The larger 66.1g specimen shows less angular rotation. Scale cube is 1 cm. I'm pretty sure these formed in the ejection phase and then re-entered the Philippines as solid bodies. Perhaps the stretched area formed on on external surface as trapped bubbles expanded and escaped during ejection, perhaps blowing the tektite apart - just an idea to explain the stretching. I do get the impression that perhaps we are dealing with a relatively runny melt sandwiched between a relatively viscous melt, which is slightly plastic and not yet solid, as oppose to a runny melt enclosed in a brittle and solid (but hot) shell, as in Indochinite Stretch tektites.

 

ABOVE: Three teardrop Philippinites from Paracale. Certainly the first two appear to have some sagging. The tail is not centrally placed, but pushed up as in many Indochinites (the thin tail cools first and the bulbous end is still molten so distortion takes place). Whilst not nearly as extreme as in Indochinites I think these show interaction with the atmosphere whilst still molten during the ejection phase. It is evident from the U-groove pattern that they re-entered as solid bodies. Perhaps these very rare Philippinites formed isolated bodies from the melt sheet at slightly lower atmospheric levels, more typical of the atmospheric levels indochinites formed at, and not as high up in the atmosphere as most Philippinites formed. Note that these are atypical compared to the majority of Philippinites that show zero sagging - even in the huge 500g to 1kg range that would have remained molten the longest! Scale cube is 1cm. These are 100% definitely Philippinites btw.

 

Going back to Indochinites. Shapes such as Hershey's Kisses must have formed whilst the Indochinite was a) still partially molten and b) travelling with at least some inherited cosmic velocity - i.e. not in a natural stable freefall orientation. In fact as these shapes formed I bet they were still travelling up! So here goes. I explain my very rare Philippinite stretch tektites and sagged forms as forming during atmospheric EJECTION. When they re-entered they were solid as evidenced by the usual core-type U-grooves on Philippinites. U-grooves are etched cracks formed in the tektite during re-entry and only form in the typical Philippinite pattern because the tektite was solid and brittle throughout. Indochinites very rarely exhibit U-grooves but can often show radial U-grooves. These are etched radial cracks. Radial cracks (found only on Indochinites and never on Philippinites) only form when the tektite interior is molten and a thin brittle exterior is present during re-entry. So, in summary, my sagged and stretched tektites must be rare forms, perhaps forming lower in the atmosphere than regular Philippinites, during the ejection phase and almost certainly did not gain their morphology during re-entry. Indochinites, that very very commonly exibit sagged forms were probably not ejected to as high atmospheric levels as Australites and (most) Philippinites.

Starburst Rays (or Starscars) vs. Radial Rays in Indochinites. Neither of these features occur in Philippinites.

ABOVE: Starburst Rays (Starscars) on the left and Radial Rays on the Right.

Starburst Rays (or Starscars) are triangular in shape and usually occur on broken tektites. The tektites broke whist still partially molten - look below the tektites are incomplete.

Radial Rays are U-grooves of a constant width. These are etched cracks which formed when the tektite had a brittle exterior and molten interior. A radial crack is often associated with the explosive loss/spalling of the anterior margin (which creates bald spots). The radial cracks often form from the anterior margin and extend over the posterior surface. They may also occur in the domed central anterior area of indochinites. 

ABOVE: Three Starburst Ray Indochinite discs. note how all the discs are broken and incomplete. The break exposed the molten interior of the Indochinite. 1 cm scale cube.

 

ABOVE: Two Radial Ray U-grooves. Note how the discs are complete. Radial rays form by etching of cracks formed during explosive spalling along the anterior margin, which creates the bald spots. Oblique views; 1cm scale cube.