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

From: kashuba <mary.kashuba_at_meteoritecentral.com>
Date: Mon, 10 Mar 2014 17:09:51 -0700
Message-ID: <001701cf3cbe$3a0bfa30$ae23ee90$_at_kashuba@verizon.net>

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 08:09:51 PM PDT