[meteorite-list] Stones with High Troilite, Low Metal

From: Carl Agee <agee_at_meteoritecentral.com>
Date: Mon, 27 Jun 2011 06:47:53 -0600
Message-ID: <BANLkTikoRCo6BocN6gPtZeAdCKmK+wNLtQ_at_mail.gmail.com>

Hi Pete,

What about an LL -- with some desert weathering? The low-low metal can
be converted to small Fe-oxides or veins.

I recently classified Northwest Africa 6588 (LL6-an), that had only
trace amounts of Fe-Ni metal. The ubiquitous sulfides present are
pendlandite and stoichiometric pyrite. See metsoc 2011 abstract:
http://www.lpi.usra.edu/meetings/metsoc2011/pdf/5418.pdf

Are you sure the sulfide is all troilite?

Carl Agee

-- 
Carl B. Agee
Director and Curator, Institute of Meteoritics
Professor, Earth and Planetary Sciences
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126
Tel: (505) 750-7172
Fax: (505) 277-3577
Email: agee at unm.edu
http://epswww.unm.edu/iom/pers/agee.html
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Message: 13
Date: Mon, 27 Jun 2011 00:31:45 -0400
From: Pete Pete <rsvp321 at hotmail.com>
Subject: Re: [meteorite-list] Stones with High Troilite, Low Metal
To: <mexicodoug at aim.com>, <meteoritemike at gmail.com>, meteoritelist
       meteoritelist <meteorite-list at meteoritecentral.com>
Message-ID: <bay153-w42304EFE707206467A6876F8570 at phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Thank you all for your responses.
You're right, Doug, too ambiguous a question.
I have an unclassified NWA, which I've sliced and polished. There are
so many interesting features that it is the type that you never get
tired of looking at under the microscope.
It has what appears to be the remains of transformed chondrules; four
total in about 2cm^2 surface.
Three look like bit-remains of brecciated chondrules, grey and white.
The other looks like a typical barred chondrule that has become
completely crystallised, and has the schiller effect.
A very fine grained matrix, no observable free metal as in
nickel/iron, and what *appears* to be typical troilite scattered
throughout.
Low attraction to a neodymium magnet.
The fusion crust is relatively fresh, with no chert.
Quite different from the others I've got, so I was hoping to read and
possibly view images of similar.
As I said, there are no silver metal flecks, only the dull yellow
troilite-looking areas.
Is it possible for nickel/iron to have this appearance, too? I had
mentally eliminated that due to the low magnet attraction, but I've
got lots to learn.
Cheers,
Pete

Received on Mon 27 Jun 2011 08:47:53 AM PDT