[meteorite-list] Metal in DaG 749 - CO3

From: Bernd Pauli HD <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:06 2004
Message-ID: <3A7F2C06.5792B1AF_at_lehrer1.rz.uni-karlsruhe.de>

Gary Hansen wrote:

> Matson's "Handbook of Elemental Abundances in Meteorites"
> says that CO's can have 3-19% metallic iron.


Hi Gary and List,

Some CO's have even higher abundances - some examples:

ALHA77003 - ca. 24.5% "t o t a l" iron
Felix, Isna - ca. 25% total iron
Kainsaz, Lancé - ca. 25.5% total iron
Ornans - ca. 25.8% total iron
Warrenton - ca. 26% total iron

NORTON O.R. (1998) Rocks From Space II, p.195:

An even more visible characteristic is the presence of iron-nickel
inclusions scattered as flakes through the meteorite. The average
CO chondrite contains about 6% by weight of metal.

and:

CR chondrites are sufficiently r e d u c e d so they contain about
10% by weight iron-nickel metal and iron sulfide. The metal content
is the most easily distinguished characteristic. The metal is found
in the fine-grained matrix AND as inclusions in the chondrules.

and Klerner states:

KLERNER S. et al. (1999) Origin of chondrules and matrix
in the Renazzo meteorite (MAPS 34-4, 1999, A 064):

Renazzo and other CR chondrites ar among the most primitive
chondritic meteorites. They have bulk compositions very similar
to C1 (CI) chondrites, except for volatile element depletions.
They contain Cr-rich metals, reflecting very reducing conditions.
The coexistence of phyllosilicate-rich matrix and r e d u c e d
metal reflects the absence of significant parent-body heating.

> Where do such droplets come from and why are they
> seen in petrologic type 3? Why not in other CCs?

As so often, Richard Norton has the key word here:

        => R e d u c t i o n <=

Best wishes and
Good Night,

Bernd
Received on Mon 05 Feb 2001 05:41:10 PM PST