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Sunday, 7 July 2013

A FEW AUSTRALITE FINDS



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 About 15 years ago I was fossicking for sapphires in Kelly’s Hut Creek, a tributary of Yarrow Creek, near Glen Innes. I noticed a dark object in the top sieve which stood out because of its regular shape. Expecting it to be a piece of black jack (pleonaste or spinel, for those who don't know the lingo), I held it up to the light and was surprised to see that it showed a pale brown colour on the edges.


This changed my thinking. It couldn’t be a piece of regular glass, because it had concentrated in the sieve centre, meaning it had at least an above average specific gravity. Nor could it have been a piece of enstatite or one of the other pyroxene minerals, because of its shape. It wasn’t as transparent as these minerals either, though the colour was similar.


At home, I was able to examine it more closely and came to the conclusion that I had found my first (and only) australite, or glass meteorite.
The same cup cake shaped specimen
Kelly's Hut Creek australite 8mm diameter


About 3 years ago while a group of us was at Rainy Swamp, again after gemstones, Jimnyjerry from ALF found a somewhat larger example. Rainy Swamp Spring Creek is also a Yarrow Creek tributary.
The Rainy Swamp australite, 12 carats


The fact that both came from Yarrow Creek tributaries is unlikely to be significant. If a shower of australites were to fall over an area of eastern Australia tonight, how many would be visible tomorrow, considering how difficult it would be to spot them on the ground in heavily vegetated areas? The ones we found were flukes, having fallen in or close to a watercourse and then ending up in our sieves the way they did.


 I won’t speculate about the origin of these little beauties, lots of other people have been doing that for well over 100 years. If you want to read up on the subject, go to Trove and search the word “tektite” in the category “Books” and “Available Online”. See my blog entry DOWNLOADING BOOKS USING “TROVE” for Tuesday 11th June 2013 for details about how to do that. There are also many newspaper articles about meteoric glass.


 
















Two books you may find useful from this source are “The Occurrence, Distribution and Age of Australian Tektites” by RO Chalmers EP Henderson and Brian Mason, 1976 and “A Contribution to the Study of Australites” by CG Thorp, 1913.


 Why not check out my You Tube channel here where you can view gem hunting, mining and general geology videos.New subscribers are always welcome.

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