[meteorite-list] Preliminary MOSS meteorite classification

From: Michael Farmer <meteoriteguy_at_meteoritecentral.com>
Date: Wed Aug 30 13:02:31 2006
Message-ID: <20060830170229.67758.qmail_at_web33103.mail.mud.yahoo.com>

Hello everyone, well here is the preliminary
classification data on the MOSS Norway meteorite fall.
Dr Jeff Grossman is doing the classification and he
sent me the following information a little while ago.
I have removed some parts of the email which is not
for public release yet, but the basics are here.
Please do not bombard him with questions, as he is
very busy working on it and it wont help.
Further work is ongoing, including oxygen isotopes and


Direct from Dr. Grossman

I now have the first probe data on "Moss," and I can
give you an
initial classification. Please remember that
chondrites are
classified not just on the petrologic characteristics,
but even more
so on their bulk and isotopic compositions (work
ongoing)
  As surprises are always
possible, I consider my classification to be
provisional.

Petrologically, Moss is a CO3. It contains
chondrules, CAIs, AOIs,
and metal/sulfide grains in the appropriate size range
(done
visually (ongoing).
The distribution of
chondrule types is typical for a CO3.

The metal + sulfide abundance is also appropriate for
CO3
chondrites. I did a point-count on a 6x6 mm area of a
thin
section. The results are shown here with data from
McSween (1977)
for all the other CO falls:

                    Metal FeS
Kainsaz (CO3.2) 5.9 1.5
Felix (CO3.3) 2.1 4.1
Ornans (CO3.4) 1.5 3.9
Lance (CO3.5) 1.3 4.6
Warrenton (CO3.7) 1.4 2.1

Moss 2.2 2.4

As for petrologic type, my initial guess of 3.5 looks
pretty
good. The histogram of Fa content in random olivines
looks generally
like one published for Ornans in 1969. Comparing to
Van Schmus's
1969 data, we get:

                   Avg Fa PMD
Kainsaz (CO3.2) 11.8 70
Felix (CO3.3) 18.4 70
Ornans (CO3.4) 19.0 68
Lance (CO3.5) 21.2 63
Warrenton (CO3.7) 33.9 21

Moss 19.9 65

This puts Moss between Ornans and Lance, although I
don't think that
difference is significant. Based on the amount of FeO
diffusion into
olivines in type I chondrules observed in the SEM, I'd
have to say
Moss is at least as metamorphosed as Lance. I'll call
it CO3.5 for
now, but I would not be surprised if further study
bumps it up to
CO3.6.

Finally, the shock stage appears to be S2 or S3, but I
haven't
classified this parameter in other CO chondrites, so
I'll have
somebody check up after me.

Jeff

I will continue sales again, now that we know it is
not a Kakangari Chondrite.


I want to thank Dr. Grossman for working so hard to
get the first carbonaceous chondrite fall in many
years classified so quickly. Specimens have been
distributed to scientists all over the country for
analysis so I expect many papers on this fall to be
written in the near future.
Michael Farmer
Received on Wed 30 Aug 2006 01:02:29 PM PDT