[meteorite-list] Tessera meteorite

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:23 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C86904EE59B5_at_US-Torrance.mail.saic.com>

Hi Mark and List,

Thank you for putting together the info page on the Tessera meteorite(s).
Prior to reading Dieter's information, I have to admit that I'd been
pretty much neutral on the subject, mostly due to ignorance. While
I'd seen pictures, I had never seen any of the meteorites in person
(and still haven't). I haven't seen any in situ images of any of the
finds, which is not to say that Matteo failed to take such images, but
if he had I would expect that we all would have seen them by now. The
lack of such images isn't so much suspicious as it is unfortunate.

Having visited Italy several times, including driving from Pisa to
Florence to Venice and on north through the Brenner Pass into Austria,
I can report that the climate is quite variable -- from hot and arid
in the south, to colder and soggier in the north. Venice gets its share
of rain (32.4" a year on average over the last 40 years), so meteorites
within 50 miles of there are going to weather fairly quickly. For
example, I wouldn't expect a meteorite to retain a W1 grade 5 years
after falling on open ground there. Yet Dieter reports that short-
lived radionuclide testing of one of the Tessera samples ruled out an
extremely recent fall. I would be curious to know what level of
confidence they place on the terrestrial age being greater than, say,
5 years; there are a number of variables, not the least of which is
the original depth of the tested sample in the meteoroid when it was
in space (cosmic ray shielding). Also, the sample that was measured
was quite small, which you would expect to have some bearing on the
uncertainty of the measurement.

The bottom line is that you have a mystery that you may or may not
be able to solve scientifically. In the absence of hard evidence,
it is tempting to apply probability, psychology and Occam's Razor
to reach a conclusion, which I'm sure many here have done. Consequently,
if I were the finder of such meteorites (essentially in my own
backyard), and lacked witnesses and/or convincing photographic
evidence of the original recovery, I certainly couldn't blame others
for being skeptical. That being the case, I would do my level best
to find *another* stone from the fall, and do as complete a job as I
could documenting its recovery -- in situ photos prior to touching
the find, photos following extraction, a soil sample from the impact
location, and a witness if possible. --Rob
Received on Mon 16 Feb 2004 04:48:32 AM PST