[meteorite-list] Acfer breccia - provisional classificationresults

From: Alan Rubin <aerubin_at_meteoritecentral.com>
Date: Fri, 12 Sep 2008 13:22:20 -0800
Message-ID: <005801c9151d$a42060b0$bc246180_at_SINOITE>

It is very unusual to have one ordinary chondrite group mixed with another.
Dimmitt (H regolith breccia) has an LL5 clast; St. Mesmin (LL regolith
breccia) has some H clasts. Let's get this thing named officially through
the Nomenclature Committee.
Alan Rubin

----- Original Message -----
From: "Rob Lenssen" <rlenssen at planet.nl>
To: <Meteorite-list at meteoritecentral.com>; <bernd.pauli at paulinet.de>
Sent: Friday, September 12, 2008 11:35 AM
Subject: Re: [meteorite-list] Acfer breccia - provisional
classificationresults


Hi List,

In January 2007, I posted a link (
http://home.planet.nl/~rlenssen/Acfer500g.htm ), pointing to some pictures
of an odd looking meteorite, asking for comments.
This request resulted - via List member Frederic Beroud - in a contact with
Jerome Gattacceca from CEREGE in France, who conducted magnetic
susceptibility measurements, and kindly offered to help to have it
classified.

Today I received (provisional) classification results, and want to share
them with you:

Provisional results by: M. Denise (MNHN)/J. Gattacceca (CEREGE)
breccia LL6-L4
shock stage S2-S4 (S2 for the LL lithology and S4 for the L lithology)
W1

Microprobe analysis (LL-L lithology)
Fayalite 31.5?0.6-25.5?0.5
Fs 26.5?0.4-22.2?0.3

So, it turned out to be an LL6-L4 breccia!
I wonder how rare this kind of breccia is, and especially if such a breccia
has special scientific value, above ""just" a mix of LL6 and L4 material".
Does anybody know an answer to this?

Kind regards,
Rob Lenssen
The Netherlands




----- Original Message -----
From: "Rob Lenssen" <rlenssen at planet.nl>
To: "Rob Lenssen" <rlenssen at planet.nl>; <bernd.pauli at paulinet.de>;
<Meteorite-list at meteoritecentral.com>
Sent: Wednesday, January 17, 2007 8:22 PM
Subject: Re: [meteorite-list] Acfer breccia


Hi Bernd + List,

As promised, I added some photographs with better resolution. I made them
through a magnifying lens. Light is not ideal, but better resolution it has.
The first three detail pictures show the area near a dark clasts. Detail nr.
4 shows a 10mm "droplett". Detail nr. 5 shows a 5mm dark spot with the
largest metalic iron spot (in the polished planes) to it's right.

http://home.planet.nl/~rlenssen/Acfer500g.htm

Hope you enjoy it + maybe get some extra info out of it.

regards,
Rob

----- Original Message -----
From: "Rob Lenssen" <rlenssen at planet.nl>
To: <bernd.pauli at paulinet.de>; <Meteorite-list at meteoritecentral.com>
Sent: Wednesday, January 17, 2007 12:05 AM
Subject: Re: [meteorite-list] Acfer breccia


Thank you very much for your reaction Bernd.

Like I wrote before, it was covered in desert varnish when I got it. The two
polished planes present fractured sides, that I planed removing as less
material as possible. Before planing they already showed dark "lumbs". Like
it fractured "around them".
Don't think it is planetary though, as it is magnetic and shows the typical
(chondrite) dots of iron in the surface.

I will try to make better pictures and will share them with you.

regards,
Rob

----- Original Message -----
From: <bernd.pauli at paulinet.de>
To: <Meteorite-list at meteoritecentral.com>
Sent: Tuesday, January 16, 2007 10:32 PM
Subject: Re: [meteorite-list] Acfer breccia


Hello Rob L. and List,

Look what I found after cleaning and polishing a desert varnish covered
Acfer:

http://home.planet.nl/~rlenssen/Acfer500g.htm

Dark clasts in lighter matrix. Also metal spots in the dark clasts.
Any idea what this might be? In chondrites I typically see lighter
clasts in darker matrix.


What a beautiful A?fer chondrite! Is it a chondrite after all? The pictures
should
have a higher resolution. Are there any chondrules? Questions, questions,
questions!

Anyway, it does look quite fresh, so it should be something like W1 or W2 at
most.
It does look highly shocked ... at least S4 but more probably S5 or even S6.
Well,
that sounds like silicate darkening. Maybe the silicate clasts were not so
very dark
prior to the shock event but experienced extensive darkening (caused by
melting of
metal-sulfide).

As for: "In chondrites I typically see lighter clasts in darker matrix"

Here are some chondrites that have dark inclusions: NWA 0869, NWA 0978,
NWA 1794, NWA 3346, OUED EL HADJAR, RICHFIELD, TANEZROUFT 061, etc., etc.

Anyway, a mighty beautiful "chondrite", something that, as Dean would now
say
"you just gotta love!" ... and if it is not a chondrite ??? Could this be a
planetary meteorite??? Questions, questions, questions!

Cheers,

Bernd




To: rlenssen at planet.nl
    Meteorite-list at meteoritecentral.com

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Received on Fri 12 Sep 2008 05:22:20 PM PDT