An odd class of tektites that formed inside bubble chambers

When it is time for a new edition, I search through our collection and inventory looking for a stone or group of similar stones with a good story to tell. Over our years of sorting through crates of tektites till our fingers were raw, we have always selected out the unusual or unique or interesting or somehow special pieces. When I am seeking inspiration for the next column, I often find myself standing over one large flat-map drawer that contains our favorite “specials”. Several previous columns in this series have featured pieces from this specimen drawer (and those pieces graduated into our living room museum cabinet!).

A few days before this was written, we won an on-line auction for a very oddly-shaped Indochinite. A really unusual specimen! (figure 2). It is not, however, the centerpiece of this column, as I have not yet sorted out its story

It sent me to the “Specials” collection drawer, looking for its classmates, (and for good measure I searched all other drawers and cabinets where such specials might be hidden) When all were gathered into one place together, some basic themes, or types, became evident that I hadn’t recognized before. Some of my favorite gems are truly one of a kind!

Kinds are important as each kind provides a record of some phenomena or special region within the impact fireball mushroom cloud. One example of anything in this context would be largely insignificant, but a repeating theme has a message worth considering.

This article focuses on a peculiar group of tektites that took their form while behaving in a low-viscosity manner that yielded ropy fold and flow character. All of these are fragmental, and most show both a smooth surface with only trace pitting and a more typical outer skin of normal pitted ornamentation (not visible in most of these photographs). It appears that most, if not all, of this kind formed inside large complex bubble cavities. (see figure 1). There they were protected from aerodynamic forces and corrosive skin pitting.

The skin textures on one or both sides are characteristically smooth and largely unpitted, like the inner surface of a bubble shard, which most clearly are, showing a typically pitted external tektite skin, separated by a thin glass wall from a smooth and sometimes ropy interior.

I had no sure idea what might lie at the end of this article, but I knew I would be learning something. Along the way, I fell in love, and with that, I would like to introduce the centerpiece of this edition’s Tektite Teaser . In the selection of this apparent “kind”, there was a rivulet of black glass flowing though a “U”-shaped channel. It resembles the look of molten tar.

 

(Point worth emphasis): the fluid behavior here showcased was happening inside an already textured shell. Classic tektite dimpling happened very early. It had already formed when still-molten streams of glass drooled down the sidewalls of dark internal bubble chambers like this extremely rare example. Characteristic tektite skin ornamentation with“beaded” hemispheric pitting was not the result of terrestrial etching by soil acids as some continue to argue, but the work of buzzing fingers of plasma (I think) even while the glass was sufficiently hot to flow.

About the Author

Norm Lehrman is a recently retired exploration geologist with over 45 years experience. His career involved fieldwork in over 35 countries on every continent except Antarctica. While stationed in Australia, Norm and his wife, Cookie, became interested in collecting Australites, which ultimately led to a generalized passion for tektites, impactites, meteorites and related materials. In 1999 they founded the Tektite Source business (www.TektiteSource.com) which has evolved into one of the world's premier providers of tektite and impactite specimens. Norm has retired to a ranch near Spokane, Washington, where they continue to serve tektite aficionados worldwide.
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