· Get a Cloudy Nights T-Shirt · Submit a Review / Article Click here if you are having trouble logging into the forums Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Speciality Forums >> Space Rocks Previous   Index   Next   Threaded   Pages: 1 zagami professor emeritus Reged: 08/22/08 Loc: The Big Sky Swarms of Micro Craters on Canyon Diablo?       #2936972 - 02/19/09 10:26 AM Attachment (40 downloads) Edit   Reply   Quote Quick Reply   Hi All, Once again, I found myself wandering the Smithsonian meteorite display in Washington DC this past weekend. This time, however, I spent more time studying the less sexy stones and irons, and instead the more common ones. One in particular caught my attention. On display is a 435kg individual of Canyon Diablo. I was on a quest to answer the question about if CD contains thumbprints or not. As I was carefully studying the surface, I noticed what I can only describe as swarms of micro craters. I tried to come up with alternate hypotheses such as mechanical disassembly like pounding on it with a hammer and chisel, but no go. They have the splashforms of craters just like are 'common' on Sikhote-Alin individuals. Here's a link to a .pdf article about the S-A impact craters: http://www.lpi.usra.edu/meetings/LPSC98/pdf/1839.pdf Below is a pic of what I'm talking about. Below that is another pic of the crater swarm, and below that is a pic of the individual in museum situ. Thoughts? Post Extras:       zagami professor emeritus Reged: 08/22/08 Loc: The Big Sky Re: Swarms of Micro Craters on Canyon Diablo? [Re: zagami]       #2936973 - 02/19/09 10:26 AM Attachment (46 downloads) Edit   Reply   Quote Quick Reply   . Post Extras:       zagami professor emeritus Reged: 08/22/08 Loc: The Big Sky Re: Swarms of Micro Craters on Canyon Diablo? [Re: zagami]       #2936974 - 02/19/09 10:26 AM Attachment (45 downloads) Edit   Reply   Quote Quick Reply   .. Post Extras:       Glassthrower Vendor - Galactic Stone & Ironworks Reged: 04/07/05 Loc: Oort Cloud 9 Re: Swarms of Micro Craters on Canyon Diablo? [Re: zagami]       #2937588 - 02/19/09 04:09 PM Edit   Reply   Quote Quick Reply   Hi Martin, Thanks for sharing this. I have seen similar pits/craters on a couple of Campo del Cielo specimens. It looked as if someone had shot the meteorite with a high-powered BB gun.....well not exactly, but that is best analogy I can make at the moment. I refer to them, arbitrarily, as "secondary impact craters" or "secondary impact pits". I haven't read the article you linked above about the Sikhote specimens, and I haven't seen any papers on this yet, but my pet theory is this : during the fall or during the explosion that ripped apart the main impactor, fragments and shrapnel was sent chaotically at high speeds in all directions. These fragments ranged in size from near-microscopic to much larger and substantial masses. These masses and fragments collided in mid air and these tiny secondary impact craters/pits are the result. AFAIK, I have not seen anything like this on a fall/find involving a single specimen. I have only seen this on large falls like Canyon Diablo, Sikhote Alin, and Campo del Cielo. Also, I think this is a process we only see in iron meteorites. I don't recall seeing this on any stony type meteorite because I expect the secondary impact would probably fracture the larger mass in such a way that it wouldn't leave a circular crater-like pit. ? That's my best guess anyway. Regards and clear skies, MikeG Post Extras:       darklighteditor Theatre King Reged: 11/07/06 Loc: Land of Sparty Re: Swarms of Micro Craters on Canyon Diablo? [Re: Glassthrower]       #2937687 - 02/19/09 04:59 PM Edit   Reply   Quote Quick Reply   That's interesting. Now I can't wait to get home to take a closer look at my 85g Canyon Diablo... Post Extras:       darklighteditor Theatre King Reged: 11/07/06 Loc: Land of Sparty Re: Swarms of Micro Craters on Canyon Diablo? [Re: darklighteditor]       #2938356 - 02/19/09 10:50 PM Attachment (49 downloads) Edit   Reply   Quote Quick Reply   Well I'll be darned... It looks at though (to my untrained eye), my 85g CD may have micro (small) craters on it as well (it's tough to tell with the sealer on it). I'll post some pics of my specimen I just scanned... Post Extras:       darklighteditor Theatre King Reged: 11/07/06 Loc: Land of Sparty Re: Swarms of Micro Craters on Canyon Diablo? [Re: darklighteditor]       #2938359 - 02/19/09 10:51 PM Attachment (42 downloads) Edit   Reply   Quote Quick Reply   same side another view. Mike, this rock should look a bit familiar to you... Post Extras:       darklighteditor Theatre King Reged: 11/07/06 Loc: Land of Sparty Re: Swarms of Micro Craters on Canyon Diablo? [Re: darklighteditor]       #2938361 - 02/19/09 10:52 PM Attachment (41 downloads) Edit   Reply   Quote Quick Reply   Flipped over... Post Extras:       darklighteditor Theatre King Reged: 11/07/06 Loc: Land of Sparty Re: Swarms of Micro Craters on Canyon Diablo? [Re: darklighteditor]       #2938364 - 02/19/09 10:53 PM Attachment (39 downloads) Edit   Reply   Quote Quick Reply   same side, another view... thumbprints?? Post Extras:       Talstarone Lunar Man Reged: 09/12/06 Loc: Pinetops, NC Re: Swarms of Micro Craters on Canyon Diablo? [Re: darklighteditor]       #2938733 - 02/20/09 06:30 AM Edit   Reply   Quote Quick Reply   Beautiful Pics,Indeed Everyone. Indeed on the Larger Pieces Of CD that have Passed Through My Hands I Have Seen Evidence Of Micro Craters,Small Craters,and The Infamous Thumbprints. There are some on the 89 gram piece I have currently... Thanks for bringing this topic to light,Martin. Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 0 registered and 5 anonymous users are browsing this forum. 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