[meteorite-list] Term Main Mass

[Jeff Grossman]

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