[meteorite-list] Iron Breccia

From: Bernd Pauli HD <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 09:55:56 2004
Message-ID: <3C59A700.5C4F7F12_at_lehrer1.rz.uni-karlsruhe.de>

Mark Fox wrote:

> Has anyone discovered or identified an iron breccia
> meteorite yet, in which two different irons unite in
> a cosmic collision?

Hello Mark and List,

What an interesting scenario! There is one meteoritic iron that
may come close to what your question implies: B a r b a c e n a

Buchwald says that the material was inadequately described in 1951
when it was classified as a "fine-finest octahedrite". Buchwald also
says that Barbacena is a plessitic octahedrite. Now, in an abstact by
Zucolotto et al. (2000) the authors confirm that there are numerous
plessite fields with features of both groups IVA (fine) and IIC
(finest).

All the IIC's I have in my database are classified as plessitic
octahedrites (ca. 0.06 mm), and the IVA's (0.20-0.42 mm)
as fine octahedrites.

Of course, this does not automatically imply that two different irons
collided in space, but, nevertheless, the average bandwidth of the IIC's
are a factor of 3 or almost 4 thinner than the width of the lamellae in
the IVA's.

References:

BUCHWALD V.F. (1975) Handbook of Iron Meteorites (Vol. 2, p. 304).

ZUCOLOTTO M.E. et al. (2000) Electron backscattered diffraction
studies of the Barbacena meteorite (MAPS 35-5, 2000, Suppl., A180).


Best regards,

Bernd
Received on Thu 31 Jan 2002 03:20:16 PM PST