[meteorite-list] Pairing discussion/questions

From: Zelimir Gabelica <Zelimir.Gabelica_at_meteoritecentral.com>
Date: Mon, 18 Jan 2010 18:46:15 +0100
Message-ID: <201001181745.o0IHjln4002369_at_smtpmul2.univ-mulhouse.fr>

Hi Greg,

This might be a typical question for Jeff Grossman.

I am also continuously puzzled by the abundance
of paired meteorites (thus those that are officially recognized as such).

Let's suppose that once one (or a few)
meteorite(s) are selected from an important lot
(as found) and sold to someone, this someone
(scientist, collector....) would envisage its classification.
And the same will possibly happen with the other meteorites from the same lot.
As a result, there will be as many different NWA
numbers, as independent classifications (of the - probably- same meteorite).
As most of these classifications probably won't
be concerted, there will not be pairings reported
and we will end up with as many different
meteorites, most probably of the same type, that
will never be suspected being paired.

If a pairing is suspected, I believe this results
from "concerted" analyses (of either meteorites
stemming from the same lot and analyzed by
different groups, or of the same meteorites
provided by different finders (buyers....)
brought for analysis to the same group).

This even complicates further if there are more
than one such "lot" found (meteorite shower
spread throughout a large strewnfield).

In case of such "concerted" analyzes, I guess
that the labs will still give a different NWA
number to each meteorite (or group of meteorites
from the same lot) analyzed, because one is never
sure that 2 meteorites supposed to come from the
same lot are at 100% the same.
If pairing is reported, then most of the time
(not always) it is mentioned in the Met. Bulls.
But because all analyzes were done independently,
each analyzed meteorite (or group of meteorites
from the same verified lot) will receive its own NWA number.

Here I realize that, at that stage, it is very
difficult to decide to only retain as official
the first NWA number attributed chronologically
and to cancel all the next NWA numbers.

I for one am just happy when pairings are
reported. This is often the case for "important"
types such as the planetaries.
But for the "common" H6's or L5's, I believe this is very seldom done.

So far, regarding my collection catalogue, here
is what I mention (for my NWA 4857 sample taken
as an example), just to have an idea of the total
mass of that meteorite evaluated so far.

NWA 4857 (Algeria, Shergottite enr maf), 0.928 g in collection; tkw:1 at 24 g:

....Paired with NWA 2975 (70.1 g), NWA 2986
(170 g), NWA 2987 (82 g), NWA 4766 (225 g), NWA
4783 (120 g), NWA 4864 (94 g), NWA 4878 (130 g),
NWA 4880 (81.6 g), NWA 4930 (117.5 g), NWA 5140
(7.5 g), NWA 5214 (50.7 g), NWA 5219 (60 g),
NWA5313 (5.3 g) and NWA 5366 (39.6 g).
Cumulated tkw: 1273.3 g (as per Jan. 2010)

I know that this neither sheds more light to the
problem, nor answers your concerns.
Hopefully someone can add more to the issue.

My best,

Zelimir


At 17:09 18/01/2010, Greg Catterton wrote:
>I have often wondered and after some discussion
>with others I wanted to get the community feeling on the issue of pairings.
>
>If a meteorite say NWA 1877 for example is out
>there and more is recovered and verified to be
>the same material from the same strewnfield,
>should the new material share the NWA number and the TKW be updated?
>I have noticed many pairings with NWA 1877 and many other meteorites.
>Same material with different numbers and TKWs listed.
>
>Would it not be in the best interest to have all
>the paired samples share on number? This would
>surely cut the amount of NWA material by 1000 or more.
>Why is this not done?
>
>What is the process for pairing material to share the NWA number?
>Is it up to the dealer or the person who did testing?
>
>What affect would it have on value if something
>with a listed TKW of 200g suddenly was paired
>with the 3 other numbers assigned to the same
>material and the TKW was pushed to 1kg or more?
>Surely it would decrease as supply grew. Is this a concern for some?
>
>I am trying to better understand the
>politics/red tape that goes with this area.
>
>Thanks, hope everyone is doing well.
>
>Greg C.
>
>
>
>
>
>
>
>
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Prof. Zelimir Gabelica
Universit? de Haute Alsace
ENSCMu, Lab. GSEC,
3, Rue A. Werner,
F-68093 Mulhouse Cedex, France
Tel: +33 (0)3 89 33 68 94
Fax: +33 (0)3 89 33 68 15
Received on Mon 18 Jan 2010 12:46:15 PM PST