Re: [meteorite-list] MPOD Feb. 20th 2014

Thanks for sharing your thoughts Elton. Especially about the thermal expansion of some constituent(s). All these working theories would be one heck of a multi-diciplinary: chemistry, aerodynamic, thermodynamic, calculus, etc, problem beyond most doctoral thesis work. Yes, it would be. And

[meteorite-list] Types of twinning in chondrites?

Hi all, I was wondering, for those that are experienced with petrology, what types of crystal twinning to do see the most in OC's? Thanks! Jim -- Jim Wooddell jim.woodd...@suddenlink.net http://pages.suddenlink.net/chondrule/ __ Visit the

Re: [meteorite-list] Types of twinning in chondrites?

The most common type of twinning in chondrules in unmetamorphosed chondrites is found in low-Ca clinopyroxenes. It is polysynthetic twinning -- it looks like the pyroxene grains have narrow stripes. These disappear when temperatures go above 630 C or so and won't be found in orthopyroxene.

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[meteorite-list] Types of twinning in chondrites?

Hello All, Jim Wooddell inquired: what types of crystal twinning do we see the most in OC's? Alan Rubin kindly posted: The most common type of twinning in chondrules in unmetamorphosed chondrites is found in low-Ca clinopyroxenes. It is polysynthetic twinning -- it looks like the pyroxene

Re: [meteorite-list] Types of twinning in chondrites?

Thanks Melinda, Alan and Bernd and all! My next question would have been; Would it be safe to say if I see polysynthetic twinning, odds are it's low-Ca cpx, but Melinda pretty much answered this. I have certainly seen this but the jury is out if I've seen other types of twinning while playing

[meteorite-list] Re-2: Types of twinning in chondrites?

My pleasure, Jim! Would it be safe to say if I see polysynthetic twinning, odds are it's low-Ca cpx, ... No, you might also be looking at multiple twinning of plagioclase but in that case you may be pretty sure it is *not* an unmetamorphosed chondrite! Bernd To: jim.woodd...@suddenlink.net

Re: [meteorite-list] Re-2: Types of twinning in chondrites?

Okay. As I said and Andy said, we can find polysynthetic twins in low-Ca clinopyroxene in type-2 and type-3 chondrites (those rocks that have not been metamorphosed). We can actually find a few such twins surviving in type-4 OC. We can see such twinning in plagioclase (also sometimes called

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[meteorite-list] Meteorite Picture of the Day

Today's Meteorite Picture of the Day: HOW 88403 Contributed by: AMN http://www.tucsonmeteorites.com/mpodmain.asp __ Visit the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com