[meteorite-list] Dean's BL chondrite - Black NWA 1685

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 25 Mar 2007 16:28:41 UT
Message-ID: <DIIE.000000C8000018FE_at_paulinet.de>

Mike T. wrote:

I would consider sending this off for classification if someone would recommend
a good institution that would be willing to look at it. This new slice has both clasts.


Hello Mike, Steve, and BL fans,

Some interesting tidbits about Dean's BL chondrite because Steve wrote:

As always nice info on this most extrordinary piece...
I really like to keep this thread going...


1. Dean believes that they are all paired because they came in together in a single
bag, they all looked the same and they also had similar magnetic qualities.

2. Bruno Fectay, on the other hand, was convinced that there were seven
different chondrites in Dean's lot (three stones of them Taouz 002, LL6).

3. Dirk Ross was also sure there were at least 3 different meteorite types involved

4. In August 2002, Dirk called upon other buyers of Dean's BL:

"Anyone wanting their NWA from Mr. Bessey classified and compared with the one
that I will classify, if interested please send 5-10 grams (enough for a thin section and
representing the variation within their stone). This will tell us if they are all paired or not.
Please include the BL#. Please contact me offline if interested."

5. Steve Witt saw less metal than in any other chondrite he had ever seen. He wasn't
even sure if it was indeed a chrondrite. He couldn't detect any chondrules in his piece.

6. Jim Baxter about BL chondrules: "Interestingly in contrast to your description mine
has quite a few chondrules scattered in the matrix, a slight predominance of glassy over
porphyritic

7. I responded:

This afternoon I looked at my cut specimen under my MBC-10 microscope and after
quite some time "discovered" what m a y be round or somewhat oval chondrules but
I am not sure ... and if they are chondrules, only a few - 3 or 4. Only a thin section*
would definitely clarify this. The chondrule presence or absence thereof is especially
interesting as Jim Baxter's specimen has quite a few, readily discernible, scattered
chondrules in contrast to my description.

* Here is my thin section decription:

Both in hand specimen as in thin section there are areas that are absolutely featureless,
devoid of any chondrules (some chondrule-like features can be vaguely seen) or other
inclusions, and look almost achondritic. The view under crossed polars is breathtaking:
While there are chondrules and mineral components of various sizes in a fine-grained,
almost opaque groundmass, the featureless clast in my TS shows an incredible, equi-
granular structure without any fine-grained, interstitial groundmass ... as if it had been
"blown" or "swept" away. Instead, hundreds and hundreds of colorful little crystalline
pearls (of olivine and pyroxene) that look as if seen from a distance.

8. With regard to the wet look of the fusion crust, Steve Witt also wrote: "In areas like
concavities where the crust was protected it appears to be v e r y g l o s s y ."


Best,

Bernd
Received on Sun 25 Mar 2007 12:28:41 PM PDT