I basically endorse the below statement by John. As for how the
NomCom uses the term "main mass," it is applied to the entity being
described in the writeup. These writeups in the Bulletin are very
specific about what material is to get each name. "Main mass" refers
back to that. If somebody wanted to put a statement in the Bulletin
like "NWA 7554 is the main mass of the NWA 6788 pairing group," I
would also find that to be an appropriate usage, and could vote to
accept it for the Bulletin.
I do differ with John on one minor point: we don't use the term only
for the largest piece in a group of meteorites assigned to a
particular number. We would also use it to describe the remaining
largest mass of a single stone that has been cut or broken up for distribution.
I also must take umbrage at the statement made in Doug's post
referring to the "not especially peer reviewed appendix of
MAPS." All articles in the supplement issue get full peer
review. Only the MetSoc abstracts do not. The MetBull is highly
peer-reviewed. The Editor and Assoc. Editors produce writeups, and a
committee of 13 scientists review each one. Many writeups also go
out for review by scientists outside the NomCom. I realize that this
is not a traditional peer review conducted by a independent editor,
but it is a very, very high degree of peer scrutiny.
jeff
At 12:46 AM 1/20/2006, Arizona Skies Meteorites wrote:
As most of us are aware, NWA numbered meteorites are
not in any way analogous to meteorites coming out of a
well characterized strewn field-that's precisely why
they are given NWA numbers. Those that understand the
NWA numbering system also understand that the main
mass of one NWA numbered group may or may not be the
'biggest piece' of the presumed "fall". In fact, the
use of the term 'main mass' in respect to NWA
meteorites has nothing to do with the 'fall' per se,
but rather is the term used to refer to the largest
piece in a group of meteorites assigned a particular
NWA number. Even the "pairing" of meteorites does not,
and can not guarantee that they are part of the same
fall. This is especially true in the case of northwest
Africa where meteorites are collected over a vast area
with little or no record of their coordinates. Since
it will never be known whether "paired" NWAs are
actually part of the same fall or not, it seems that
the term main mass is appropriate unless one can
unambiguously state with complete certainty that two
NWA numbers are from the same fall. This can not be
done without a precise record of coordinates. In our
opinion this discussion over the use of "main mass" is
just a matter semantics, and has nothing to do with
science what-so-ever. That said we can probably bring
this thread to an end.
Cheers
-John
Dr. Jeffrey N. Grossman phone: (703) 648-6184
US Geological Survey fax: (703) 648-6383
954 National Center
Reston, VA 20192, USA
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