[meteorite-list] Zacatecas (1792) on ebay

From: Jason Utas <meteoritekid_at_meteoritecentral.com>
Date: Sun, 17 May 2009 22:44:33 -0700
Message-ID: <93aaac890905172244y346ff3dcv6ce2e441c523573b_at_mail.gmail.com>

Hello Mike,

http://www.encyclopedia-of-meteorites.com/test/Zacatecas1792_don_edwards.jpg

Clearly recrystallized, the piece on Don's site looks like a slice of
the 1969 individual. The trouble is that if that really is a piece of
the 1792 fragment, then the one on ebay isn't a piece of either iron.
Hmmmm....
I'd say that the picture you found is a slice of the 1969 individual,
mislabeled.
Regards,
Jason


On Sun, May 17, 2009 at 10:36 PM, Michael Fowler <mqfowler at mac.com> wrote:
> Thanks Jason,
>
> Don Edwards has a photo in the encyclopedia of meteorites, but it is not
> very clear. ?I was trying to decide if it was the re-crystalized 1969
> Zacatecas or the 1792 one. ?I'm inclinded to think it is the 1792 Zacatecas,
> but there is room for confusion.
>
> http://www.encyclopedia-of-meteorites.com/test/Zacatecas1792_don_edwards.jpg
>
> Mike
>
>> Hello Mike,
>> Indeed, that's not a piece of the more common Zacatecas (1969).
>> See here; that iron is clearly recrystallized:
>>
>> http://www.nyrockman.com/museum/zacatecas-1462.htm
>>
>> While I haven't been able to find a picture of the etch of the
>> Zacatecas (1792) iron, I was able to find this picture of the main
>> mass:
>>
>> http://commons.wikimedia.org/wiki/File:Zacatecas_(1792)_meteorite.jpg
>>
>> There is more than one Zacatecas!
>> Regards,
>> Jason
>>
>> On Sun, May 17, 2009 at 9:52 PM, Michael Fowler <mqfowler at mac.com>
>> wrote:
>>
>> > I collect ungrouped irons, and am looking for a slice of Zacatecas
>> > (1792) an
>> > ungrouped iron.
>> > The specimen on ebay:
>>
>> >
>> > http://cgi.ebay.com/Meteorite-ZACATECAS-1792-perfect-etched-slice-12-3g_W0QQitemZ270389277772QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef474f44c&_trksid=p3286.c0.m14&_trkparms=66%3A2%7C65%3A3%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A5%7C294%3A50#ebayphotohosting
>>
>>
>> > does not in my opinion look like the photo in Buchwald, or match his
>> > description:
>> >
>> > "Zacatecas is remarkable in that it belongs to the rather few
>> > polycrystalline iron meteorites. ?The grain size ranges from 1 to 5 cm,
>> > a
>> > variation which is partly due to the random sectioning through many
>> > almost
>> > equiaxial grains. ?....... ? The grain boundaries are also conspicuous
>> > because of the copious development of very irregular 1-3 mm wide zones
>> > of
>
>> swathing kamacite. ?This kamacite was nucleated by the troilite and
>>
>> > schreibersite precipitates, and by the boundary itself, and grew
>> > significantly before the bulk of the grains transformed during the
>> > primary
>> > cooling period.
>> > ......
>> > Zacatecas may have shown a kamacite bandwith ot one time of .6 -1.0 mm,
>> > but
>> > since all taenite eventually disappeared and significant grain growth in
>> > the
>> > kamacite took place, no well defined Widmanstatten pattern is present
>> > now.
>> > ?In this respect, Zacatecas resembles New Baltimore, Santa Rosa and
>> > Chihuahua City."
>> >
>> > So in short, no well defined Widmanstatten pattern, unlike the photo in
>> > the
>> > ebay ad.
>>
>> > Would anyone like to comment?
>>
>> > Thanks,
>>
>> > Mike Fowler
>>
>> > Chicago
>
>
>> ebay--starsandrocks______________________________________________
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Received on Mon 18 May 2009 01:44:33 AM PDT