[meteorite-list] blue chondrule in a CM2
From: Zelimir.Gabelica at uha.fr <Zelimir.Gabelica_at_meteoritecentral.com>
Date: Sat, 06 Feb 2010 23:20:08 +0100 Message-ID: <20100206232008.rz1pahn6vps8wcs8_at_w3mail.univ-mulhouse.fr> Hello Jeff, Matthias, Ted, all, Your wise suggestions about the blue inclusion are highly appreciated. I also first thought of hibonite that was mentioned in a similar discussion we had on the list a couple of years ago. At the time, Jeff Kuyken showed us a chondrule-like inclusion in Isheyevo and hibonite was one of the hypotheses retained . I don't really remember the detailed discussion that resulted but this info is now probably hidden somewhere in the archives . By luck, this debate (with hibonite hypothesis) as well as the inclusion pics are still available on Jeff's site (Jeff K, I hope you don't mind if I provide the link): http://www.meteorites.com.au/features/isheyevo.html The blue color in Isheyevo (as it is in Allende shown by Ted), is more intense than the light blue shade of our TNZ "chondrule" so I did not retain at first that hypotheis. (also because all the terrestrial hibonites I have seen are dark brown but more often just black; the best crystals so far come from Madagascar and I have in my mineral collection a 6x4x3 cm single cristal, just full black- from the famous Betroka deposit). I now realize the hibonite hypothesis is very likely. But enstatite is another possibility indeed. I have a terrestrial enstatite sample that is blue-green. The synthetic enstatites we once had synthesized in the lab are logically white. Two last questions (sorry for insisting): 1) Should we consider this just as a curiosity or does someone believe this could have some pertinent significance in the case of a CM2 chondrite ? 2) How can we make sure the "round light blue circle" shown here is a chondrule or a CAI ? Jeff firmly states that the TNZ hibonite is embedded in a CAI and Ted shows the same in Allende. Would that imply the TNZ "circle" is also a CAI rather than a chondrule, despite of its quasi perferctly round shape ? My best wishes, Zelimir Ted Bunch <tbear1 at cableone.net> a ??crit??: > Dear Zelimir- Jeff beat me on the response. > > Attached is a true hibonite in an Allende CAI. Your blue object could be a > lighter blue hibonite or an enstatite chondrule that, on occasion, has a > blue hue depending on the light source, angle of illumination, light > scattering, etc. > > Ted > > > On 2/6/10 10:06 AM, "Zelimir.Gabelica at uha.fr" <Zelimir.Gabelica at uha.fr> > wrote: > >> >> Hi List, >> >> Here are 3 pics of a genuine blue chondrule spotted upon breaking a >> fagment of the CM2 meteorite Tanezrouft 082 (purchased last June in >> Ensisheim, from A. Gouesslain/J.-L. Parodi, the meteorite finders). >> >> See here: >> >> http://www.agab.be/question/question.html >> >> Question: what could be the origin of such a strange turquois-like >> blue color ? >> >> Could it be due to some traces of Cu2+ salts neutralizing some >> refractory silicates ? (despite tha fact that the presence of Cu was >> apparently not reported in the meteorite analysis, see the Met. Bull. >> writeup added in the URL). >> >> Or could that just be (sometimes) the natural color of some >> (ortho)pyroxenes ? >> >> Or olivine ? >> However, I don't remember having ever seen any olivine showing such a >> "true" blue color. Shouldn't olivine (always?) rather be >> "olive-green", whatever its origin (terrestrial or asteroidal) ? >> >> Thanks for sharing your thoughts or expertise. >> >> My best, >> >> Zelimir >> >> >> ______________________________________________ >> 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 Sat 06 Feb 2010 05:20:08 PM PST |
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