Dear John I posted a very similar message about 6 months ago, without great success... So here is my personal feeling: it looks unlikely statistically that two different R3.8 or R4 come out of NWA, but not impossible : there are 2 nakhlites and 4 shergottites in NWA. It is true that 753 and 978 or 800 and Ouzina show different weathering and "colors", but this happens on different pieces of the same fall.
What I would bet very highly unlikely is that more than 2 different R3.8 or R4 exist! No type of detailed study can solve the problem definitely, as even if every chemical and petrographic features would be the same in 753 and 978 for example, it does not tell for sure that they are the same fall: they may be different fall from the same "asteroidal outcrop"; there are many examples of that in ordinary chondrites (undistinguishable different falls). Once again we touch the major drawback of NWAs: no precise location means unsolvable incertitude in pairing. We can just talk about probability and with the squeletic R population, statistics are nearly meaningless. (My unconvinced bet is that 753 and 978 are the same fall, but I would not be surprised of the opposite) Pierre ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
