[meteorite-list] Weird inclusion in NWA 2086 CV3

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Tue, 10 Aug 2010 23:57:43 -0400
Message-ID: <AANLkTi=sW8-HHRjKHWQiBgEoiURMKhYMH0H=KcN6mhh2_at_mail.gmail.com>

Hi Jason and List,

Jason makes a great point about this being an "inclusion within an
inclusion". These specimens were taken from a small, jagged, fragment
that was obviously a remnant of a larger mass. Before that mass
fragmented (either in flight, on impact, or through weathering), it
was presumably a whole stone with a more representative lithology of
this meteorite. This light-colored region with squashed chondrules
and it's brown "inclusion" was previously embedded in the larger
stone. It would have been great to see a slice of the whole stone
that this fragment came from.

As for being NWA 2086 or not, I would question it also if presented
with my initial post and photos. But, I did cut a larger batch of
this material and all of it (except for this fragment) looked exactly
like typical NWA 2086 - darker matrix, more spherical chondrules, more
colorful chondrules, CAI's, etc. Also, I asked my source about the
chain of provenance regarding this batch and I was told that it came
directly from a very respected source. I don't want to name drop, but
contact me off-list if curious. The provenance is very solid. So I
am very confident that this material is indeed NWA 2086.

The question in my mind now is about the brown inclusion - is it a
product of weathering/oxidation, or was it originally present in the
meteorite? If the latter, then what is it? This question will be
answered soon, because one List member has offered to thin-section
this material for me and another list-member with thin-section
experience purchased the largest piece. So, two different veteran
list members are going to make qualitative examinations and analysis
of these specimens in the future. And I hope they will share the
results with us.

Also, for those who might inquire, this "brown inclusion / light
lithology" material is sold out. I kept one slice and sold the
remaining pieces. All I have remaining are small crumbs and a few
sub-gram pieces that show some chondrules. The slice I kept will
likely become another thin-section, pending further discussion.

I did some looking on the web, and I found a single photo of NWA 2086
that has a clast that somewhat resembles the lighter lithology in my
specimens. In this linked photo, look in the lower left-hand portion
of the specimen, near the 7-oclock position. You will see a clast on
the edge that is a different lithology than the rest of the specimen.
The clast is similar in color to my specimens, but it lacks the
squashed ellipsoidal chondrules.

http://www.meteorite-house.com/MHContentFiles/MHmetPix/PicStoneCHotherNWA208611.html

I examined my slice under the microscope at 60x tonight, and the
matrix in the light-colored area looks "stippled". It appears to be
composed of tiny black dots set into a whitish background matrix.
Whatever it is, it is very fine-grained compared to the darker
lithology that is seen on the same specimen. I am glad there is the
boundary line and region of common NWA 2086 lithology in these pieces,
because it provides a good contrast for comparing the two lithologies.

Best regards,

MikeG

------------------------------------------------------------
Mike Gilmer - Galactic Stone & Ironworks Meteorites
http://www.galactic-stone.com
http://www.facebook.com/galacticstone
------------------------------------------------------------



On 8/10/10, Jason Utas <meteoritekid at gmail.com> wrote:
> Hello Jeff, All,
> The only reason that I assumed that this slice *might* be a piece of
> NWA 2089 is because of that "dark corner" - it's the only part of this
> stone that looks *like* NWA 2086.
> The light lithology that you say looks like NWA 2086 looks very unlike
> other samples of 2086:
>
> http://www.aerolite.org/prizes/nwa-2086.htm
>
> http://www.meteoriteguy.com/catalog/nwa2086.htm
>
> http://www.meteorite-times.com/Back_Links/2008/march/Accretion_Desk.htm
>
> So what we're looking at here, if it's a piece of NWA 2086, is a slice
> comprised almost entirely of a light clast that is in no way typical
> of most NWA 2086 specimens.
>
> That strange brown thing that everyone's arguing about has chondrules
> in it. If it has discolored differently than the rest of the
> meteorite due to weathering or some other process, it would still
> point towards that area being composed of a different material (why
> would it weather differently if it were made of the same stuff?).
> Given that it seems to have a lesser concentration of chondrules
> within it (as opposed to the rest of the lighter clast), I would
> assume that it is indeed foreign meteoric material.
>
> But CV3's have strange C-type inclusions in 'em all the time. What's
> the biggie?
> ...It's an inclusion within an inclusion? That's cool...
>
> Regards,
> Jason
>
> On Tue, Aug 10, 2010 at 1:07 PM, Jeff Grossman <jgrossman at usgs.gov> wrote:
>> My money's on terrestrial weathering as the cause of the brown area,
>> although there is a clear lithologic boundary on the right side of photo:
>> http://i268.photobucket.com/albums/jj24/Meteoritethrower/2086-slice-weird-1.jpg.
>>
>> Jeff
>>
>>
>> On 2010-08-10 2:22 PM, Galactic Stone & Ironworks wrote:
>>>
>>> Hi Bernd and List,
>>>
>>> That's funny you mention that because Bob King also raised the
>>> possibility of phyllosilicates. I took some more photos of the
>>> specimen that show a better representation of what the specimen looks
>>> like. You can also see a distinct boundary line between the typical
>>> NWA 2086 lithology (darker matrix) and the strange "lighter colored"
>>> lithology that the majority of this stone has. One area near the end
>>> shows the type of matrix we expect from NWA 2086.
>>>
>>> The brown inclusion does not show any features under it or through it,
>>> except in one small spot where two chondrules appear to be immersed in
>>> it, while the rest of the inclusion flows around the chondrules like a
>>> river flows around islands.
>>>
>>> http://i268.photobucket.com/albums/jj24/Meteoritethrower/endcut-519-a.jpg
>>>
>>> http://i268.photobucket.com/albums/jj24/Meteoritethrower/endcut-326-1.jpg
>>>
>>>
>>> http://i268.photobucket.com/albums/jj24/Meteoritethrower/2086-slice-weird-1.jpg
>>>
>>> Best regards,
>>>
>>> MikeG
>>>
>>> ------------------------------------------------------------
>>> Mike Gilmer - Galactic Stone& Ironworks Meteorites
>>> http://www.galactic-stone.com
>>> http://www.facebook.com/galacticstone
>>> ------------------------------------------------------------
>>>
>>> On 10 Aug 2010 15:21:51 UT, bernd.pauli at paulinet.de
>>> <bernd.pauli at paulinet.de> wrote:
>>>
>>>>
>>>>
>>>> http://i268.photobucket.com/albums/jj24/Meteoritethrower/2086-inclusion.jpg
>>>>
>>>> Hello All,
>>>>
>>>> Michael G. wrote:
>>>>
>>>> "So I am thinking that there must have been a surface fracture that
>>>> extended
>>>> down into
>>>> the interior of the stone. Weathering products intruded through this
>>>> crack
>>>> and the brown
>>>> 'inclusion' is probably just a clay-like replacement mineral."
>>>>
>>>> "clay-like" => phyllosilicates are clay minerals!
>>>>
>>>> .. and *if* it is preterrestrial, this might be an extended
>>>> area of phyllosilicates, saponite, smectite or something!
>>>>
>>>> Cheers,
>>>>
>>>> Bernd
>>>>
>>>>
>>>>
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>>>>
>>>
>>> --
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>>>
>>
>>
>> --
>> Dr. Jeffrey N. Grossman phone: (703) 648-6184
>> US Geological Survey fax: (703) 648-6383
>> 954 National Center
>> Reston, VA 20192, USA
>>
>>
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Received on Tue 10 Aug 2010 11:57:43 PM PDT