[meteorite-list] [AD]: NWA 8276 - the "NOT SO" ordinary chondrite L3.00/W1 (and the start of an interesting discussion?)

From: Carl Agee <agee_at_meteoritecentral.com>
Date: Mon, 10 Mar 2014 19:33:53 -0600
Message-ID: <CADYrzhrMDwyu9h+veQ2e8Pi=RZkYSEaMZz_fDzVv9tmkwKRcQg_at_mail.gmail.com>

Yes, I think you are hung-up on shock! Please take a look at the
MetBull entry if you want see an example of highest quality write-up
(JMHO). We literally included the "kitchen sink" on this one,
publication quality data set -- mainly because a 3.00 doesn't come
along every day.

Best regards,

Carl Agee
*************************************
Carl B. Agee
Director and Curator, Institute of Meteoritics
Professor, Earth and Planetary Sciences
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126

Tel: (505) 750-7172
Fax: (505) 277-3577
Email: agee at unm.edu
http://meteorite.unm.edu/people/carl_agee/



On Mon, Mar 10, 2014 at 6:09 PM, kashuba <mary.kashuba at verizon.net> wrote:
> Mendy, Adam, List,
>
> Congratulations on discovering this special rock. I saw it in Adam's room
> in Tucson and we talked about it. A 3.00 calls to every collector. But
> there was no shock rating so I was reluctant to buy. There was another
> valuable stone at another dealer that I passed on for the same reason.
>
> Maybe I'm stuck in tradition, but when I'm considering a shocked stone, I
> like to know how shocked it is. When I'm considering a pristine chondrite,
> I want to know how pristine. That includes the effects of thermal
> metamorphism, aqueous alteration, terrestrial weathering and shock. None of
> these is necessarily a deal breaker, but each plays into my seat of the
> pants cost-benefit deliberation.
>
> Semarkona is considered unshocked and unequilibrated. It is spectacular in
> thin section. It's hard to know what NWA 8276 L3.00 W1 would look like.
>
> Sincerely,
>
> John Kashuba
> Bend, Oregon
>
> -----Original Message-----
> From: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Mendy
> Ouzillou
> Sent: Monday, March 10, 2014 12:35 PM
> To: Met-List; Adam Bates
> Subject: [meteorite-list] [AD]: NWA 8276 - the "NOT SO" ordinary chondrite
> L3.00/W1 (and the start of an interesting discussion?)
>
>
>
> Hello everyone, The NWA desert continues to thrill us this with unique and
> amazing specimens. NWA 8276 is just such a meteorite. It is the second L3.00
> and is "possibly" paired to NWA 7731. NWA 8276 features a rich, black crust
> and a yellowish matrix densely packed with chondrules. Extensive analysis by
> Dr. Carl Agee and Karen Ziegler support the 3.00 classification - a
> classification that indicates no heat or aqueous alteration of any kind (at
> least as far as can be presently evaluated). In fact, this meteorite
> represents material from the earliest history of our solar system. Older
> than CAIs? Not sure, but maybe Dr. Agee can chime in.
>
> The complete writeup may be found here:
> http://www.lpi.usra.edu/meteor/metbull.php?sea=3.00&sfor=types&ants=&falls=&
> valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All
> &mblist=All&rect=&phot=&snew=0&pnt=Normal%20table&code=59487
>
> The
> explanation how this meteorite was identified makes for a short but very
> good read (from MetBull):
> "Adam Bates identified this meteorite from images he received as a possible
> pairing to NWA 7731,even though they came from a different Moroccan
> meteorite dealer. Both pieces were then purchased within a few weeks of each
> other in October 2013."
>
> Adam Bates and I partnered on half the stone and anxiously awaited for Dr.
> Agee's results. It was not a given that this was in fact paired with NWA
> 7731, especially since the meteorite was bought from a completely different
> dealer. There were visual differences in the stone that led Carl to
> initially believe that 8276 may be different from 7731. In the end, the
> classification came back as L3.00 but with enough differences to state that
> NWA 8276 is "possibly" paired with NWA 7731. The terrestrial weathering is
> also
> quite low and only an W1.
>
> Many people state meteorites as being rare, but some are certainly rarer
> than others. The type 3.00 classification has only been given to 3
> meteorites: Semarkona (LL3.00), NWA 7731 (L3.00) and now NWA 8276 (L3.00).
> Here is an excerpt from Dr. Agee's FB discussion with David Weir on the 3.00
> classification and the rarity of this material:
> "Grossman and Brearley (2005)define the subtypes less than 3.2 as 3.15,
> 3.10, 3.05, and 3.00. [This scale is] primarily based on the mean value and
> standard deviation of Cr2O3 in coarse ferroan chondrule olivines. I'm not
> saying that the Grossman and Brearley scheme is the ultimate, but it is
> simply the standard currently. What will really improve the subtype 3
> nomenclature (and understanding of unequilibrated OCs) are more samples like
> NWA 7731 and NWA 8276. Up to now we have so few in the 3.15-3.00 range that
> the statistics of small numbers makes it hard to have meaningful
> subdivisions. I would gladly use an even finer scale (i.e. 3.01, 3.02, 3.03,
> 3.04 etc.) if it were actually established. The Grossman and Brearley (2005)
> scale is the only one that exists with any sort of sampling to anchor it. We
> just have too few samples to establish a finer scale. And when one starts
> talking about all the possible subtle differences around 3.00, I'm not sure
> if a
> numerical, linear scale would even make sense. The nice thing about
> discovering more of these very low type 3s is that more will hopefully be
> available for research. Semarkona, because much of it resides in India and
> some at the Smithsonian (I believe), it is hard to get a hold of. For
> example we only have a couple thin sections of Semarkona at UNM -- not even
> a tiny fragment!"
>
>
> The items for sale (and pricing) may be viewed at
> http://www.meteoritesusa.com/meteorites-for-sale-4/nwa-8276-l3-00-w1-a-remar
> kable-and-scientifically-important-meteorite/
>
>
> The photos have had no color manipulation and represent the true colors of
> this meteorite as viewed under studio lighting (5500K). Anyone interested in
> acquiring material may contact me by responding privately to this email or
> to Adam Bates (sales at bcmeteorites.com). The transaction and any associated
> details will be kept strictly confidential.
>
>
> Regards,
>
> Mendy Ouzillou
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Received on Mon 10 Mar 2014 09:33:53 PM PDT