[meteorite-list] My oddball UNWA revealed in photos

From: Michael Gilmer <michael_w_gilmer_at_meteoritecentral.com>
Date: Mon, 23 Feb 2009 17:01:15 -0800 (PST)
Message-ID: <453973.27915.qm_at_web58401.mail.re3.yahoo.com>

Hi Listees!

I got my strange UNWA back from cutting today. It has been cut in
half and the inside is finally revealed. First, a little backstory
to explain what caught my eye.

On the outside it looks like a million other weathered UNWA
stony chondrites. But notice the shiny "veins" that are revealed
on the surface of the specimen. They look different than the
rest of the stone. At first glance it could be remnant fusion
crust, but it's not. It appeared to be a vein of metal or oxidized
metal, or glassy shock/melt material that weathered slower than
the rest of the specimen. It should also be noted that the
specimen is strongly attracted to a magnet.

On the interior, several features stand out -

1) the matrix is similar to Al-Haggounia 001. It looks like
enstatite, but upon closer inspection it appears to be some
form of more familiar chondritic material. It has prolific metal
grains, but they are very tiny. Most of the metal flecks I have
seen in UNWA OC's is more coarse grained - the metal in this
meteorite is much finer, and is only apparent as a general
glittering when held in the hand and turned under a light. The
metal grains are not easily discerned until you see them with a
10x loupe. The matrix is a deep brown to light tan with black
grains that contrast the sparkly metal and enstatite-like pale
grains.

2) There are numerous veins that run through the matrix like rivers. In fact, they resemble a large river delta as seen from a satellite photo. They appear black when looked at straight on, but are very reflective/shiny when held at an angle - like fresh pencil graphite on glossy black paper. The veins are attracted to a
magnet and appear to have stronger attraction than areas with
little or no veins.

3) there are a few faint relict chondrules and one large obvious
chondrule. The large obvious one is white and is located near
one edge. There are also a few distinct grey chondrules that are
very small and can be seen in the close-up photo I posted - they
are located very close to the large white chondrule, between
the white chondrule and the edge of the specimen. There is also
an apparent black chondrule nearby. Otherwise, chondrules are
not seen in the majority of the matrix. Chondrules are mostly
present in the areas of the matrix where the veins are sparse or
not present.

4) there is no noticeable or distinct border or dual lithology - the differences between the chondritic portion and the EL-like portions of the matrix are subtle.

After looking at the photos and reading this description, would
anyone care to guess what petrologic type it might be? Any
observations or comments would be appreciated. Is this a shocked
OC with glassy/melt veins, or is it some kind of EL-type meteorite related to the Al-Haggounia/NWA 2828 types? Or is it some kind of highly-oxidized transitional chondrite with mesosiderite-like features? Does it contain Andromeda strain?

Link to the gallery of photos -

http://s268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/

Links to individual photos -

The whole stone (notice the "veins" ??) - http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/unwa-weird-1.jpg

Another photo of the whole stone - http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/unwa-weird-2.jpg

Closeup of the matrix and "veins" (notice the big white chondrule and smaller grey/black chondrules nearby) - http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/unwa-weird-3-close-1.jpg

Both halves showing the matrix - http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/unwa-weird-halves-1.jpg

Exterior, showing the "veins" - http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/unwa-weird-vein-1.jpg

Another interior matrix shot - http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/unwa-weird-vein-2.jpg

Another interior photo showing the veins - http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/unwa-weird-vein-3.jpg

Photo of the veins reflecting light at an angle - http://i268.photobucket.com/albums/jj24/Meteoritethrower/Meteorites/Anomalous/unwa-weird-vein-reflect-1.jpg

Thanks for taking a look! :)

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
..........................................................




      
Received on Mon 23 Feb 2009 08:01:15 PM PST