Bernd wrote: <<As for this wedge-shape piece with no pattern at all, I can only guess that it is a severely heated, melted, and recrystallized inclusion or it might be a plessitic field...I have been waiting here for someone like Eric or Ron to jump in.>>
I don't offer an explanation. However, I have seen this often before. Many years ago, Ron Oriti ( a meteorite collector and once head-guide at the Griffith Observatory) purchased a Gibeon from, of all places, a rock shop in Hollywood, California. I forget the weight but it was probably around 500 kilos. He sliced it like a loaf of bread, rendering slices perhaps 12-18 inches across. (I forget exactly as it was 30 years ago or more.) It was not uncommon to see a discontinuity where apparently crystallization proceeded from different regions with the Widmanst�tten patterns oriented differently, and approached an interface between them. Its not so much a wedge, but rather a zone between the two areas where there is no pattern, and this zone can be several cm. wide. As I have never possessed one of these of my own (Oriti would never sell his old friend one as he wanted more money than I could afford!) I couldn't pursue the interesting structuring question. I however, have seen several of these slices, and I understand that he still has a number left. This is the best I can offer on this. Ron Hartman ----- Original Message ----- From: Bernd Pauli HD <[EMAIL PROTECTED]> To: meteorite-list <[EMAIL PROTECTED]> Sent: Monday, March 18, 2002 11:31 AM Subject: [meteorite-list] Deformed Gibeon patterns > Anne wrote: > > > Vincent's Gibeon is amazing! > > Hello Anne and List, > > I agree and so is yours, Anne! > > > I picked up another odd one in Tucson. It looks as if it was made of > > 3 different pieces: 2 have nice Widmanstatten patterns, but oriented > > differently, and then there is wedge-shape piece with no pattern at > > all. It is now on my site: > > > www.impactika.com/meteorites/gibeonslice.html > > > How do you explain that one? > > I wish I could and I have been waiting here for someone like Eric or > Ron to jump in. Let's start with the easier part of the affair: the two > Widmanst�tten patterns which are oriented differently and that Gibeon > slices are so famous for. They represent 2 original taenite grain bound- > aries. A slice with a diameter of about 50 cm may show up to 9 different > taenite grain boundaries and thus as many different orientations of the > Widmanst�tten pattern. > > As for this wedge-shape piece with no pattern at all, I can only guess > that it is a severely heated, melted, and recrystallized inclusion or it > might be a plessitic field. > > Best wishes and ... > waiting for other > list members' comments! > > Bernd > > ______________________________________________ > 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
