[meteorite-list] Term Main Mass

From: Arizona Skies Meteorites <johnbirdsell_at_meteoritecentral.com>
Date: Thu Jan 19 23:32:54 2006
Message-ID: <20060120043252.2621.qmail_at_web51507.mail.yahoo.com>

Adam this has got to be one of the stupidest things
you've posted to this list. The NWA numbering system
really isn't all that complicated. Just to help you
out Adam, each and every NWA numbered meteorite has a
MAIN MASS. For you, Adam that would mean the
B-i-g-g-e-s-t piece. Maybe you have heard of a
publication called the 'Meteoritical Bulletin'?

Here's an excerpt from MB89 to help clarify things for
you. Pay particular attention to the last three words.


"Northwest Africa 2373 Northwest Africa Purchased
2004 August Martian (olivine-phyric shergottite)
Several small stones that weigh 18.1 g were purchased
in Erfoud Morocco. They are yellow brown with desert
ablation/varnish surface only, no fusion crust.
Description and classification (T. Bunch and J.
Wittke, NAU): olivine phenocrysts (<1.25 mm in
longest dimension) set in a fine-grained groundmass
(<0.1 mm) of pigeonite, maskelynite, chromite,
Ti-magnetite, augite, chlorapatite and sulphide.
Olivine has cores of Fa30.7 (FeO/MnO = 51.9), rims of
Fa50.3 (FeO/MnO = 53.3) and contain micron to
submicron inclusions of chromite, glass, and barite.
One large olivine grain, which may be a xenocryst, is
different from the rest with a core of Fa29.1
(FeO/MnO = 43) and more abundant tiny inclusions. The
wide (0.2 to 0.4 mm), inclusion-free mantle on this
grain is Fa32.3 (FeO/MnO = 39.2). Pigeonite is zoned
from Fs29.4Wo8.4 to Fs36.4Wo14.1 (FeO/MnO = 28);
augite is Fs21.8Wo29.1. Maskelynite is slightly zoned
with a compositional average of An52.1Or2.1.
Chromite, cr# = 87, fe# = 90.4. Overall texture,
mineral content and mineral compositions strongly
suggest that this stone is paired with NWA 1068. The
specimen is lightly weathered and moderately shocked.
Specimens: type specimen, 3.7 g and one thin section,
NAU; main mass, Birdsell."

Now Adam are you suggesting that the Scientists that
write these classifications, the Nom Com and the
editors of the Meteoritical Bulletin are somehow
"misleading" and "dishonest"?

 

Kind regards



-John




--- Adam Hupe <raremeteorites_at_comcast.net> wrote:

> Dear List,
>
> I noticed some dealers and collectors are calling
> pairings that are smaller
> than the largest piece of a pairing series the "Main
> Mass". An example
> would be if an 8 kilogram Martian meteorite was
> called DAG 476. Then
> somebody comes up with a smaller 1 kilogram
> meteorite named DAG XXX which
> was found to paired to DAG 476. Then the dealer
> sells the 1 Kilogram DAG
> XXX as a "Main Mass." I think this practice is
> misleading and dishonest. I
> think the term "Secondary Largest Mass" may be more
> appropriate.
>
> What do you think?
>
> Adam
>
>
>
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Arizona Skies Meteorites
Received on Thu 19 Jan 2006 11:32:52 PM PST