[meteorite-list] Meteorite Pairing Discussions

[Zelimir Gabelica]

Hi John,

NWA 4024 is indeed a nice example of the 
discrepancy between Met. Bull. data and the 
amount of stuff circulating on the market.

This is perfectly illustrated if you compare the 
Met. Bull. write up regarding NWA 4024 an look at 
the photos included at the end of the same report.
There are some 15 pieces illustrated, coming from 
various sources. Although weights are not 
mentioned, a rough evaluation of the volume of 
the pieces (comparison with the scale cubes) 
leads to evaluate that the total weight of the 
illustrated pieces should largely overstep 100 g, probably more.
Not mentioning that the pieces pictured probably 
represent only a small fraction of what is really 
available as 'NWA 4024" in collections.

I have in collection a 4.43 g end section (got from Hanno Strufe).
But my own write up states that Mike Farmer 
reported at the time (2006) that the tkw was at least 745 grams.
He explicitly explained this discrepancy by the 
following argumentive comment: "first piece sold, 
more pieces come out", which is, as we know, not really a surprise.

Nothing is mentioned officially about pairings 
and I don't know whether this meteorite is also 
being sold under another NWA N° but I guess the 
pics in the Met. Bull. suggest that all the 15 pieces were called "NWA 4024".

The tkw of a meteorite is indeed rarely updated 
officially (by the Nom Com and thus reported in 
the Met. Bulls.) probably because nobody writes 
them to update the old tkw. I agree that the Nom 
Com should not be blamed for that.

As a typical example (among many others) the 
official tkw reported in Met. Bull. for Chiang 
Khan is still 367 grams, while everybody now agrees that it is of several kg.
When helping Mike Jensen to update the 2008 
edition of  "Meteorites from A to Z", I reported 
him several such examples and, in some obvious 
cases, the actual tkw was updated (with, as 
reference: "numerous sources including internet, 
personal communications and professional experience".
Needless to say that this updating is not 
official because not (yet ?) agreed by the Nom. Com.
For the cited example of Chiang Khan, we agreed 
to the put, as tkw, 75+ at 7.0+ kg, which is more 
realistic regarding the present market, although 
not official as I agree only the Met. Bull. (Nom. 
Com.) should act as official reference.

There is some pertinent work needed here and I am 
convinced many of us from the List and elsewhere 
can help in trying to provide more correct figures to the Nom. Com.

Zelimir


At 04:38 19/01/2010, John.L.Cabassi wrote:
>G'Day List
>This has been a very interesting read. Quite some time ago, I brought up
>the question about NWA 4024, which apparently on the card that
>accompanied it and the Met Bull stated a TKW of 38.1g.  But there's
>definitely alot more out there ??? Is there pairing going on here?
>
>http://tin.er.usgs.gov/meteor/metbull.php?sea=nwa&sfor=names&ants=&falls
>=&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&cat
>eg=Winonaites&mblist=All&rect=&phot=&snew=0&pnt=Normaltable&code=34296
>
>
>And now for another, I purchased this off of Tom some time back. NWA
>231, the met bull lists is as being provisional, it has yet to be
>classified. The main mass was 1054g. What I have is 1048g, 6 grams are
>missing; I think due to polishing a window. But I confirmed with Michael
>C.  and it was confirmed. The label on the rock states "NWA 231" so
>everything checks out. But it's yet to be classified. I have not found
>the time to go ahead with this, but I was curious that NWA numbers were
>handed out prior to being classified.
>
>http://tin.er.usgs.gov/meteor/metbull.php?sea=nwa+231&sfor=names&ants=&f
>alls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name
>&categ=All&mblist=All&rect=&phot=&snew=0&pnt=Normaltable&code=31470
>
>Any thoughts?
>
>Cheers
>John
>IMCA # 2125
>
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Prof. Zelimir Gabelica
Université 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