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NWA xxx   contributed by Steve Brittenham, IMCA 2184   MetBul Link


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View all entries for   Meteorite (76)   Steve Brittenham (109)


Copyright (c) Steve Brittenham.
The largest piece measures 80 x 70 x 23 mm and weighs 173.9 grams; the pair weighs 239.0 grams in total.   unclassified

Steve writes:
Seven years ago I was at Edwin Thompson’s home going through four large flats of unclassified NWA individuals he’d purchased earlier at the Tucson Gem and Mineral show. I wasn’t expecting much as these flats were already high graded by a few scientists who’d recently spent a fair amount of time going through them, but at a dime a gram I figured if I were lucky enough to find a few fun cutters, it would still be worthwhile (plus, I love looking at any kind of meteorite!). The flats each contained several layers of stones, and because I spent way too much time looking at every one – often with a loupe trying to discern any potentially interesting features – it took several hours to get through all four boxes. Fortunately Edwin has always been so accommodating of my indecisiveness when trying to pick between multiple choices!

The smaller piece in today’s submission was found buried at the bottom of the first flat I’d looked through – it was the only sliced one there – and while being disappointed that I wouldn’t have the joy of cutting it myself and being pleasantly surprised by the “reveal”, I couldn’t pass up the interesting forked shock vein that bisected the contrasting whitish material near one end (first photo). Then (much!) later, I found in the third box its larger sister which, unlike the first piece, had significant amounts of fusion crust and even a couple of regmaglypts (second photo).

The largest piece measures 80 x 70 x 23 mm and weighs 173.9 grams; the pair weighs 239.0 grams in total. While the two halves fit closely together, it was interesting to see the change in the shock vein’s characteristics and included material over just the width of the saw cut (third photo). Although I was initially only looking for cutters, aesthetically these pieces appealed to me so it was hard not to add the pair to the four uncut individuals I also purchased.

As an aside, Tom Phillips showed me an intriguing way to quickly identify the presence of shock melt in the fusion crust of an uncut stone by using cross-polarized light; I’m working on a portable device for doing this, which would make sorting through flats of meteorites to find interesting cutters like this one a lot quicker!


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Steve Brittenham
 5/2/2017 12:27:26 AM
Jansen, so sorry I got your name wrong in my prior reply (I know it's no excuse, but I have a friend named Jason and I guess I just went into automatic). My apologies.
Steve Brittenham
 5/1/2017 2:45:18 PM
Hi Meteorite and Bernd. I'm not sure if the CML folks actually missed these pieces due to the sheer volume of rocks in the boxes, or whether they just felt some of the others they did take were more aligned with their interests. I was just happy they left them for me to find! Jason, glad you liked the crust -- me too, it's one of my favorites! And Anne, I'm not sure if I want to cut pieces off to have it classified; I doubt it's anything unique, and it's kind of nice having both intact halves to show when I do school presentations. Still, a local fellow has an XRF, so it might be fun to play a bit . . .
Anne Black
 5/1/2017 12:03:38 PM
Yes, that crust is unmistakable. Now will you get it classified?
Jansen Lyons
 5/1/2017 10:11:52 AM
That crust made me gasp! What an amazing NWA XXX piece, and that crust would automatically over-rule the sedimentary sentimentality. Awesome share, thanks a ton!
Bernd Pauli
 5/1/2017 6:01:17 AM
But photo #2 would immediately teach them better!
Meteorite
 5/1/2017 12:55:30 AM
Nice one, Interesting is that if you show that to some "university meteorite experts" as soon as they see those strait line of shock vein*s ,Sadly they would respond that : this is sedimentary rock .
 

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