Hello David > So after melting and recooling on Earth do they really > maintain the pattern >or is it only present on pieces large enough not to melt?
Yes as Frederic explained, only the surface and a thin layer below is heated. The passage thrue the atmosphere takes only a few seconds, so the heating is intense but short. If it was heated (as far as I remember above aprox. 700 deg. C. )all the way true the meteorite, there would be no Widmanstatten patern. Yes Sikhote-Alin�s do have a very coarce pattern, in fact the patern can be so wide that a slice looks like it has no patern at all. Best wishes Lars Pedersen ----- Original Message ----- From: "meteoriteshow" <[EMAIL PROTECTED]> To: "David Hathaway" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Tuesday, December 16, 2003 12:31 PM Subject: Re: [meteorite-list] Patterns in Sikhote-Alin > Dear David, > > Melting while crossing the atmosphere is "superficial". Meteorites lose a > major part of their weight (less for irons than stones) that burns away to > ashes, but the inside of the meteorite remains at space temperature (i.e. > abour -270�C). This is the main reason whay they often break into fragments > in the atmosphere (because of high stresses due to temperature difference > btween the inside and the "burning skin"), and actually this is what > happened to Sikhote Alin, providing numerous fragments. As almost of all > them show regmaglypts, this means that it happened in the high atmosphere, > high enough to allow the fragments to keep on burning for a while. But the > inside did not melt. For smaller fragments, the inside most probably heated > up, but not to melting point. > This is my understanding, and should I be wrong, please do not heasitate to > let me know as I'm always open to learning more! > > Frederic Beroud > www.meteoriteshow.com > IMCA #2491 > ----- Original Message ----- > From: "David Hathaway" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Tuesday, December 16, 2003 7:28 AM > Subject: [meteorite-list] Patterns in Sikhote-Alin > > > > I am a little curious about something..... > > > > I heard that the sikhote-alin meteorites have a Widmanstatten Pattern > > although large and difficult to see. > > > > I have also heard that the regmaglypts are created when a molten piece > cools > > while airborne.. As nearly all the fragments I have seen have regmaglypts > I > > assume all these pieces have been molten. > > > > So after melting and recooling on Earth do they really maintain the > pattern > > or is it only present on pieces large enough not to melt? > > > > > > > > ______________________________________________ > > Meteorite-list mailing list > > [EMAIL PROTECTED] > > http://www.pairlist.net/mailman/listinfo/meteorite-list > > > > > > ______________________________________________ > Meteorite-list mailing list > [EMAIL PROTECTED] > http://www.pairlist.net/mailman/listinfo/meteorite-list ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
