[meteorite-list] Micrograph gallery post Lunar crust and Lodranite
From: cdtucson at cox.net <cdtucson_at_meteoritecentral.com>
Date: Thu, 27 May 2010 12:06:43 -0400 Message-ID: <20100527120643.P6AL0.541005.imail_at_fed1rmwml41> Tom, You said. "If I found this in all fresh crust, then I would be onto some thing. " I'm not sure what you mean? To me it seems nothing is ever exactly the same in any meteorites. Why should it be? No two rocks are the same. Not all irons show a dendrite texture or a Widmanstattan figures pattern or Neumann lines pattern or a smooth featureless pattern and in the latter three the nickel apparently has something to do with it. But with Dendritc crystals nickel content has nothing to do with it. Many iron meteorites display the dendritic pattern (RBT 04162 and 04299 ) to name two and yet so do many iron objects that contain NO nickel. The point being that again that nothing is ever the exact same all of the time. It seems the best we can hope for is that sometimes things work out right. In this case your micrograph states a good case that the crustal area melted and the interior did not. If this is even sometimes the case then in those cases it is an argument that the rock's exterior spent time melting. What better than travel through our atmosphere to cause that to happen to a rock? How ever seldom it works out. Again 2 more cents here. Carl -- Carl or Debbie Esparza Meteoritemax ---- Starsinthedirt at aol.com wrote: > Thanks Carl, I think you are right but I have grown shy of making large > sweeping claims. When ever I do, I just learn what I don't know. > > I would say that in some instances, melted material from entry remains on > the meteorite. But as it has been long accepted that the trailing edge of > an oriented stone can accrete some material, this may not be a significant > observation. If I found this in all fresh crust, then I would be onto some > thing. > > A couple years ago I wrote a Micro Vision article for Meteorite Times > Magazine called Crystals in the Crust" It was centered on NWA 2371 H4. I > chose this meteorite because of the very cool inclusion on the edge of my > sample. Sort of crystals in the crystals! The image clarity was not as good > back then and the focus seemed to be on the inclusion structure and not the > dentrites. > > Perhaps I should make an update to the NWA 2371 Gallery post. For now, > any one who wants to see a few of those "New" images, just email me. I will > embed (Reduced!) several images and try to send one full size as an > attachment. Due to file size only one full size file can be sent at a time and > even at that, some of the ISP's will not allow a file that big. > > Thanks for the interest. > > Tom Phillips > > In a message dated 5/27/2010 8:32:44 A.M. Mountain Daylight Time, > cdtucson at cox.net writes: > Tom, > On a serious note with regard to the dendrites found in Lunar fusion > crusts. > This is not only amazing to look at but, you may have stumbled upon > something of significant importance here. > It has always been a chore to determine whether what appears to be fusion > crust is actual fusion crust or perhaps something else. > The choices include Fusion crust, desert varnish and weathering rind to > name a few. > In iron meteorites this dendritic texture is proof of melting. Many irons > display this texture throughout the entire meteorite again as proof that > it was once molten. > Your discovery of this texture found only on the exterior of this lunar > meteorite seems to be sufficient proof that only the exterior of this Lunar > meteorite actually melted? As you point out that this texture is only seen > in the crustal area of the meteorite. > Although this may be an anomaly and may not occur in all fusion crust. One > thing may be certain. If it does occur there maybe melting going on. This > would be far different than what occurs in the forming of a desert varnish > or a weathering rind. > So, in summary. It seems to me this could be a significant aid to our > Scientific community in initial determination and analysis of what is going on > with respect to fusion crusts. And ultimately add to the proof that the > rock was once in space. What else would cause only the exterior portion of a > rock to melt? Fusion crust is key in recognizing meteorites and this new > discovery may have just made recognition a whole lot easier. > Perhaps all crusts could be checked at this great magnification to see if > they too have this texture. > Even if this texture is not always present in crusts at least when it is, > there would be no doubt about how it formed and what it is. > This could save valuable microprobe time as it does not cost much money to > look at the crust at a high magnification. If it has this texture the > Scientist knows he needs to continue to study. > Back in the day. I do know that David Kring would always require that > polished thin sections would always include the fusion crust area for > observation. So, is this a well kept secret and scientists already look for this? > It would be great to see how often this texture actually does occur in > crusts of stony meteorites. I know I have thin sections with crust but, no > high power microscope. Tom, perhaps you could lead the charge on this. Maybe > start a service to check crusts prior to sending them off to Scientists. > This could weed out at least some of the junk? > Great job Tom. > Carl > > > -- > Carl or Debbie Esparza > Meteoritemax > > > ---- Starsinthedirt at aol.com wrote: > > Hi List, Paul (Meteorite Times) has worked his magic and set up two > new > > articles on my meteorite micrograph gallery. > > > > The first is NWA 6075 Lodranite found at > > > > http://www.meteorite.com/meteorite-gallery/articles/nwa-6075/ > > > > > > The second is a set of very high magnification images of a Lunar crust > on > > NWA 2977. There really are crystals in this crust! It can be found > at > > > > http://www.meteorite.com/meteorite-gallery/articles/nwa-2977/ > > > > I previously posted some of these shots on Face Book and some of you > may > > have seen them but many more have been posted in my gallery. > > > > Please take a look and comments are appreciated! > > > > Tom Phillips > > > > ______________________________________________ > > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > > Meteorite-list mailing list > > Meteorite-list at meteoritecentral.com > > http://six.pairlist.net/mailman/listinfo/meteorite-list >Received on Thu 27 May 2010 12:06:43 PM PDT |
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