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Roll Overs:
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#4
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Copyright (c) Steve Brittenham.
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137 gram individual. unclassified
Purchased in 2011 from a U.S. meteorite vendor.
Sadly, Professor Eno Lirpa (4/1/2016) is AWOL this year. He was supposed to send a contribution but he is currently on a super-secret expedition and is super-paranoid about revealing his location. He did write that his daughter, Loof, and his Meteorite Recovery Specialist, Jack Sack, are engaged :)
Steve writes:
Several years ago I acquired an otherwise non-descript 137 gram unclassified stone NWA to practice cutting meteorites. I used a 5" Ameritools rock saw to halve it, which cools the diamond blade with water. I'd just purchased a 1.3 MP camera for my low magnification zoom microscope and decided to try taking a few pictures of the cut surface (affordable camera technology back then wasn't as good as today's, so I apologize for the mediocre quality of the photos). I wiped the meteorite dry, then set it aside for about fifteen minutes while I mounted the camera to the eyepiece and booted up the computer.
To my surprise, my first look through the microscope showed several growths that had obviously appeared after cutting, presumably "fed" by the water used to cool the blade. Photo 1 is a collage of five of the larger ones taken at various angles and magnification.
Photo 2 shows enlargements of the growth labeled 'A' in Photo 1 (at a bit over a mm in diameter, it was the largest of those photographed). The bottom two photos were taken from the side to better show how it protruded above the cut surface. Photo 3 shows three others (labeled 'E', 'D', and 'B' respectively in Photo 1), the left and middle best demonstrating the hollow nature of these growths. Many seemed to have formed around darkened areas of the matrix – it wasn't clear whether the darkness was intrinsic to the meteorite or whether these areas were more porous and still retained some moisture.
In some ways the texture of these growths was reminiscent of those 4th of July snakes that "grow" as they burn. I didn't initially probe any of them to test how hard they were – I'd planned do that after taking more pictures. But I paused to process some of the initial shots I'd already taken and when I returned to the microscope, all of the growths had dissolved back onto the surface of the meteorite. Subsequent searches for others proved futile, though Photo 4 shows some crystals seen in one of the vugs elsewhere on the meteorite's surface (the two images were taken at slightly different focus points).
The entire lifespan of these growths was on the order of 90 minutes, so it was only by luck that I saw them in time to grab a few photos. I don't know how common this kind of thing is when cutting stone meteorites, but I personally haven't observed subsequent growths on any of the dozen or so I've personally cut since this one. It would be fun to hear of others' similar observations in any they've cut.
Click to view larger photos #1 #2 #3 #4
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Nhoj Ssiblevid
4/1/2017 6:34:38 PM |
Meateoric Smeggmaa. I beweeve tis wuz ready pruven ubout 10 yeres a go. chears frum UAE |
Steve Brittenham
4/1/2017 2:39:41 PM |
Thanks MexicoDoug. And Happy April Fools Day to you too (and everyone else). Jesper's description was interesting and reminiscent of things I've seen on irons too, but since the growths on this stony were white and there wasn't any obvious metal around them, I'm wondering whether your explanation isn't the more likely one (particularly since there are no fjords here in Boise, Idaho, nor very much humidity in the air either!). Also hopefully you saw my belated comment in response to your question about Lake Murray's age (sorry, I'm still keeping an eye out for the actual reference). |
MexicoDoug
4/1/2017 1:54:51 PM |
When in doubt the obvious is usually the best initial guess. My take on obvious is calcium carbonate predominantly in a mix of Cal-Mg salts and whatever else is picked up in the NWA desert basin that forms caliche. And just for fun, what could explain the mysterious disappearing act? You used tap water (a high pH). As the water is exposed on the large surface area of the slice the crystals disappeared corresponding to the uptake of CO2 and subsequent acidification, so the crystals re-dissolved at the new lower pH. Unless you used ice water from a fjord, I would use that as the working hypothesis. You made stalagmites and then they dissolved from acid rain :-) |
MexicoDoug
4/1/2017 1:41:52 PM |
Hello Steve, happy April 1, and thanks for substituting for our esteemed colleague Eno Lirpa! This is purely speculative since we cannot recreate your unrecorded conditions, but In would discount iron (II) chloride since you'd get a mix of Fe (III) chloride which would color the crystal darker and it would have at least been green. Iron usually forms colorful crystals and there is no large source of chlorine here. Tap water is perhaps 20 ppm at most ...which is not much, considering the residue from water is mainly calcium salts. |
Steve Brittenham
4/1/2017 10:56:43 AM |
Hi Jesper. Thanks for that input. I'll do some research on it. That's what's great about resources like this - so many people willing to share their knowledge. I wonder if the chlorine came from the water to cool the blade (I didn't use distilled).
I also have a "bleeder" that I'll submit sometime. It would consistently wick water in just a few spots. Interesting interior when cut, but nothing to explain the wicking.
And I didn*t realize my submission was posting on April Fool*s Day, but I can assure everyone that while these photos were indeed taken several years ago in April, it was on the 25th and not the 1st :) |
Jesper G
4/1/2017 5:16:41 AM |
I think it might be ferrous chloride. The meteorite might have been exposed to cl in the ground, before it was found.
I have seen gray, yellow and brown growths on iron meteorites, before they were stabilized.
Best regards
Jesper 4925
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