[meteorite-list] Carancas Thin sections

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 07 Oct 2007 21:01:26 UT
Message-ID: <DIIE.000000B500002078_at_paulinet.de>

Sterling wrote:

"People who understand thin sections are invited to comment in reply"

Hi Sterling and List,

Unfortunately these thin section pics are very low-resolution so it is hard
to judge from these low-quality pictures. But let's try and others, like John
Kashuba, are invited to chime in.

The dark areas in the cross-polarized image are probably opaque minerals
(metal, troilite, etc.) and the conclusion we can draw is that this meteorite
is metal- and FeS-rich, in other words an H5 or H6 chondrite (I think Mike
Farmer already said so in one of his first mails).

On the left, in the nine o'clock position there is a small, circular chondrule
that has a thick, igneous rim of, well, I guess olivine (vivid purplish red) and
pyroxene (blue tints ... pigeonite ???).

Between this chondrule and an even smaller chondrule right of center (tiny BO
chondrule???), there is a "conglomerate" of what may have been one or several
large BO chondrules (chondrule fragments). This causes a bit of headache because,
if this is or was a large BO chondrule, I wouldn't rule out an L chondrite as H
chondrites tend to have smaller chondrules!

Right above center, there is what looks like a POP (porphyritic olivine-pyroxene)
chondrule about the same size as the one in the nine o'clock position.

The overall texture is that of a recrystallized chondrite (H5 or H6, L5 or L6)
but as the chondrule in the 9 o'clock position is relatively unaltered as is the
small one right of center, I'd say it might be an H5 or an L5.

Best wishes,

Bernd (who neither owns Cali nor Carancas)
Received on Sun 07 Oct 2007 05:01:26 PM PDT