[meteorite-list] NWA 4024/2680

From: Marcin Cimala <marcin_at_meteoritecentral.com>
Date: Tue, 19 Jan 2010 16:01:06 +0100
Message-ID: <65275C23A119482CBE5E347C68F84A39_at_polandmezrd5i9>

Hi
You can add to this also my number NWA 5980. Its paired to 4024
TKW 298g

-----[ MARCIN CIMALA ]-----[ I.M.C.A.#3667 ]-----
http://www.Meteoryty.pl marcin(at)meteoryty.pl
http://www.PolandMET.com marcin(at)polandmet.com
http://www.Gao-Guenie.com GSM: +48 (793) 567667
--------[ Member of Polish Meteoritical Society ]--------




> Hi Jason,
>
> Excellent link for NWA 4024 compared to 2680 (Birdsell).
> From what I just can discern, I am convinced 2680 is exactly the same
> material as 4024.
> See, as comparison, the pics of both meteorites added at the end of their
> respective Met. Bull reports (although NWA 2680 is still provisional,
> there are pics attached).
> In particular Mirko Graul provided pics of both.
> Here they are, for comparison:
>
> NWA 2680:
>
> http://tin.er.usgs.gov/meteor/get_original_photo.php?recno=5645813
>
> and NWA 4024:
>
> http://tin.er.usgs.gov/meteor/get_original_photo.php?recno=5645817
>
> Very similar slices, almost same pattern (look at details!)
>
> My modest suggestion:
>
> Owing to the fact that NWA 2680 is still provisional, why not suggesting
> to this specific classification working team (Zolensky & al ?) to conclude
> (after a thorough re-examination) that both meteorites are the same and
> thus also consider to maintain only one NWA number, thus that NWA 2680 is
> identical to NWA 4024 (that should have priority because first
> classified)?
>
> But here the question is perhaps even more complicated because NWA 4024 is
> said to be a winonaite, while it now appears obvious that only one (or a
> few) achondritic clast(s) were analyzed in it, not the (major ?) iron
> found all around (that is IAB ungr.).
> It would then be wise to fully re-analyze both materials (ideally by the
> same team) and conclude.
> If there rises evidence that both are the same, then I guess there should
> come an agreement for a common type and name ?
>
> Sorry, I am not in the Nom Com nor I know how they would proceed in such a
> case, so perhaps my suggestion is very naive.
> I therefore expect more comments from Nom Com experts and am ready to
> humbly accept their conclusions whatever they be.
>
> This is here only one typical example of something that could still be
> done, because NWA 2680 is not yet official.
> There are probably other such favorable examples.
> Solving them, even if progressively, will push the pairing problem one
> step forward, though it is obvious, as Jeff pointed out, that this pairing
> problem is really very difficult (I'd say impossible) to solve completely.
>
>
> Zelimir
>
> At 12:56 19/01/2010, Jason Utas wrote:
>>Hello John, Zelimir, All,
>>I've held samples of both; NWA 4024 is indistinguishable from NWA 2680.
>>
>>http://www.arizonaskiesmeteorites.com/AZ_Skies_Links/NWA_2680/index.html
>>
>>http://www.meteoriteguy.com/catalog/nwa4024.htm
>>
>>It was likely misidentified the second time around because the sample
>>sent in for analysis was too small for an accurate study - or perhaps
>>the person who performed the analysis simply wasn't expecting an iron.
>> Either way, it's funny - an analysis based solely on the study of a
>>clast that comprises at most ~30-40% of the total volume of the
>>meteorite...I've never seen that done before.
>>It's a IAB with silicate inclusions - a pretty one, but an example
>>that's not crazily different from a few already-known irons. Oh, and
>>it has winonaite-type silicate inclusions. Just like Campo del Cielo
>>and many other IAB's...it's pretty typical in that respect.
>>We purchased a ~40g individual as a new iron in Tucson three or four
>>years ago; there were hundreds of small individuals of this iron
>>available at the time, totaling at least several kilograms (most
>>weighed only a few grams; Dean Bessey sold some of them on ebay later
>>that year, again, misidentified, and mixed with small mesosiderite
>>fragments). In Tucson they were being sold as Zagora; we were
>>surprised to find a very fine pattern after we removed an end from
>>ours for analysis.
>>Based on what I have seen personally, I would estimate the TKW of the
>>find to be at least ten kilograms, but knowing NWA, there could be
>>(and likely is) much, much more.
>>Regards,
>>Jason
>>
>>On Tue, Jan 19, 2010 at 2:58 AM, Zelimir Gabelica
>><Zelimir.Gabelica at uha.fr> wrote:
>> > 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
>> > 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
>> > ______________________________________________
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>> >
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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
> ______________________________________________
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Received on Tue 19 Jan 2010 10:01:06 AM PST