[meteorite-list] Opinions on an oddball meteorite I cut open

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Wed, 1 Jul 2009 12:55:16 -0400
Message-ID: <e51421550907010955u7a462c1fod1cd7959209f1737_at_mail.gmail.com>

Hi Jason, Eric and List!

I want to classify promising meteorites in the hopes of adding
something to science - no matter how small that contribution might
seem. Plus, I haven't done it yet, so I am eager to "break the ice"
and get a classification under my belt. I have a box of whole stones
and a few fragments (like this one) that I have culled out of my bulk
lots over the last 2 years. These are stones that have some odd
aspect to them - strange appearance, very low magnetism,
chondrule-rich, oriented, etc. Now that I have a saw, I am windowing
these stones. Thus far, most have been disappointingly common on the
inside with the typical weathered H-chondrite matrix. But this one
was unexpected. I expected it to be a meteorwrong, or to have a
weathered interior. I was surprised to see an apparently fresh (or
semi-fresh) matrix with extremely tiny metal flecks (more like
pinpoints) and some remnant chondrules that look re-crystallized or
heat metamorphosed. I saw a photo of an L7 that looks similar to this
matrix, but the similarity is solely aesthetic I am sure.

When I saw "very low magnetism", I mean this - I have a N48 rare earth
magnet cylinder that is pretty good sized. (1 inch tall and about .75
inch diameter). It's very strong and common H chondrites will leap to
it. I have other small meteorites that are the same size as this
oddball stone, and they leap to the magnet and stick strongly. This
meteorite barely sticks at all. The meteorite will attract to the
magnet, but if I pick the magnet up the meteorite will fall off - the
attraction is not strong enough for the meteorite to remain stuck.
Out of all the UNWA stones I have in my oddball box, this one shows
the least attraction. I wish I had some real objective method to
quantify the magnetic attraction, but this arbitrary description is
the best I can do.

As far as classifying small stones - the latest MAPS Met Bulletin in
print shows the results of the last Chinese Antarctic expedition. One
classified specimen is a single chondrule. Several American Antarctic
finds are less than 1 gram. (from previous bulletins). I think if
we, as collectors, dismiss promising stones because of their small
size, we run the risk of missing rare types that science could benefit
from. As long as a flood of tiny pointless classifications doesn't
paralyze the system, I don't see the harm in classifying specimens
similar to this. AFAIK, many labs are still accepting material like
this.

Since I am new to cutting open stones, I was wondering if a matrix
like this is more common than I realized. I have seen some pretty and
interesting results from cutting, but this is the only one that didn't
immediately scream "H chondrite". I have another stone with a
beautiful matrix that resembles marbled ice cream with chondrules and
metal fleck, but despite it's beauty, I am relatively certain it is on
OC. It's a keeper just the same.

If anyone is interested in seeing a slice of this grey oddball UNWA, I
will send one for study - if someone with a petrographic microscope
and experience can make a more specific determination on what this
stone might be. Contact me offlist if interested.

Best regards and thanks for the feedback,

MikeG






On 6/30/09, Jason Utas <meteoritekid at gmail.com> wrote:
> Hola,
> Check out the last picture - there's a white chondrule clearly visible
> in the upper right/center of the photo.
> Also note the dark chondrule (large, but fuzzy) at the bottom edge of
> the slice, a tad to the left of center.
> I'd go with LL6; it has a few chondrules, and from what I understand,
> the type seven designation is reserved for primitive achondrites. Of
> course, it's hard to gauge L vs LL, but you did say that the magnetism
> was "very low."
> Regards,
> Jason
>
> On Tue, Jun 30, 2009 at 2:11 PM, Galactic Stone &
> Ironworks<meteoritemike at gmail.com> wrote:
>> Hi Listees!
>>
>> I'd like some opinions on a meteorite I cut open yesterday. It's an
>> oddball I've had in my box of NWA for some time - awaiting a date with
>> the saw. It exhibits a very low magnetism and it has a grey matrix
>> almost entirely devoid of chondrules - although there does appear to
>> be some remnant chondrule structures. I'm hoping it might be some
>> kind of achondrite, but the magnetism mostly rules that out. Is it
>> some uncommon type like an L7? Or is it just something common that I
>> have not seen before?
>>
>> The exterior has a wind polished desert varnish on it and there
>> doesn't appear to be any fusion crust to speak of - although there are
>> a few scattered tiny patches of black on it. The stone weighs 16
>> grams. I only made 2 cuts - I cut one corner off to expose the matrix
>> (endcut) and I made one thin slice. The rest of the stone is intact.
>>
>> Here are some photo links -
>>
>> http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/new-odd-cut/odd-new-1.jpg
>>
>> http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/new-odd-cut/odd-new-2.jpg
>>
>> http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/new-odd-cut/odd-new-3.jpg
>>
>> Any opinions are welcomed.
>>
>> Best regards,
>>
>> MikeG
>>
>> --
>> .........................................................
>> Michael Gilmer (Louisiana, USA)
>> Member of the Meteoritical Society.
>> Member of the Bayou Region Stargazers Network.
>> Websites - http://www.galactic-stone.com and http://www.glassthrower.com
>> ..........................................................
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>

-- 
.........................................................
Michael Gilmer (Louisiana, USA)
Member of the Meteoritical Society.
Member of the Bayou Region Stargazers Network.
Websites - http://www.galactic-stone.com and http://www.glassthrower.com
..........................................................

Received on Wed 01 Jul 2009 12:55:16 PM PDT