Rhett Bourland wrote: > My 8 cents
Hello Rhett and List, Those 8 cents are well spent :-) > I also know there are large sections of iron in this chondrite that are > unlike any other meteorite out there. These large sections of irons will > display a Widmanstatten like most iron meteorites when etched. To be able > to form the necessary bands in the pattern would require that this meteorite > was formed deep within the asteroid so that there would be plenty of > insulation (in the form of rock) to keep the heat in the inside of the > asteroid so that the kamacite and taenite would have the needed time > to grow large enough to show up when etched. > Early in the H parent body's history a pretty good sized impact happens > on the H parent body. Its powerful enough to disrupt the asteroid to its > center but not necessarily powerful enough to break up the asteroid. > When it does this, some of the free metal in this region pools together > to form the large metal veins. KRING D.A., HILL D.H., GLEASON J.D., BRITT D.T. et al. (1999) Portales Valley: A meteoritic sample of the brecciated and metal-veined floor of an impact crater on an H-chondrite asteroid (MAPS 34-4, 1999, 663-669): Summary of the authors' conclusions: 01) Portales Valley has unusually large veins of metal and pockets of metal produced by intersecting veins. 02) Provenance of these veins: a) produced by an impact event on the original H-chondrite parent body, or b) a large asteroid produced from the fragmentation of that parent body. 03) Cooling rate about a few to perhaps tens of degrees per million years for the products of that shock metamorphism. 04) The meteorite was deep within the H-chondrite body at the time of the large impact event. 05) The crater diameter was >= 20 km in diameter (about 10% of the original H-chondrite parent body). 06) The impact event probably occurred about 4.4 or 4.5 Ga, soon after accretion from the solar nebula. Best regards, Bernd ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list