[meteorite-list] NWA 2871: Rocks From Space Picture of the Day - November 5, 2007

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 05 Nov 2007 21:41:19 UT
Message-ID: <DIIE.000000A000002282_at_paulinet.de>

Doug kindly wrote:

"Just a click away and an interested person without the materials and
microscope can vicariously participate with Bernd's clear and colorful
image of his nice thin section of Lodranite/Acapulcoite material."


Thank you, Doug. Much appreciated! Yes, that's one of my best pics
that I've taken so far in cross-polarized light and still without a gadget
to firmly attach the camera to the microscope, camera only hand-held!

Doug: "Bernd, could you kindly mention which of the grains were measured for those
of us who want to confirm our little fun with a tape measure on our computer screens?"

I could but I won't ;-) Let me explain my rudeness: You have the field of view
in the upper right corner, so it's easy to figure out the rest - an easy exercise!

Doug quoting from C. Floss: "The simple bimodal classification of these meteorites
based primarily on petrographic criteria, which has been used to date, appears to be
inadequate to describe this diverse group of samples, ..."

Hence I wrote and also quoted on Friday, Oct 26:
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But: It is not only grain size! ... and that's why this excerpt
from an article in MAPS may be of interest in this context:

TERRIBILINI D. et al. (2000) Evidence for common breakup events of the
acapulcoites-lodranites and chondrites (MAPS 35-5, 2000, pp. 1043-1050).

"GRA 95209 is considered a lodranite based on petrography (McCoy and
Carlson, 1998), but Mittlefehldt and Lindstrom (1998) find that the bulk-rock
composition is more similar to acapulcoites and quite different from that of
lodranites. Thus, a clear-cut classification is difficult."

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Best wishes,

Bernd
Received on Mon 05 Nov 2007 04:41:19 PM PST