Re: [meteorite-list] ¿ ventifacted ?

From: Nicholas Gessler <gessler_at_meteoritecentral.com>
Date: Wed Jan 19 17:57:45 2005
Message-ID: <6.2.0.14.2.20050119144244.050190e0_at_mail.ucla.edu>

Hi,

Yes, "wind faceted" (wind and sand ablation) seems to be the key feature of
relevance. If you look at photos of the alleged meteorite found on Mars,
it contains quite a few facets. And the ridges between the facets are very
sharp. I have seen hard quartzite and flint-like rocks on deserts with the
same sharply delineated features. The ventifacted chondrites, on the other
hand, do not show these facets or sharp delineations. Neither does the
banded iron example or the other iron meteorite from Antarctica.

As far as I know, these sharply delineated facets occur with wind and sand
from a constant direction over a long period of time. And the material has
to be hard and homogeneous. Consequently I wonder what a terrestrial iron
meteorite would look like subjected to the same conditions? I have a new
NWA iron that is otherwise round and smooth but clearly shows those lines
but no facets. I'm sure it was attacked by water and by wind and sand, but
how much by each I just don't know. I suppose even a solid hunk of
non-meteoric iron subjected to the same conditions would answer the
question. Unless the rock found on Mars is an ataxite, I would also expect
that any attack (whether by acid or wind and sand) would reveal some
evidence of Widmanstatten lines. I don't see any evidence of that in the
Martian photograph.

So as much as I think it's a keen idea to find a meteorite on Mars, I'm not
convinced. "Extraordinary claims require extraordinary evidence." So my
questions are:
a) Why does the Martian rock show faceting? Does that support or detract
from the claim that it is an iron meteorite?
b) Exactly what analysis was done on Mars? I have only seen the most
general reports for PR purposes. Can anyone point me to a more definitive
report? Do we have access to the thermal heating and dissipation data, for
instance? And what else?

Cheers,
Nick
Received on Wed 19 Jan 2005 05:57:32 PM PST