[meteorite-list] Martian Sedimentary Meteorites
Sterling K. Webb sterling_k_webb at sbcglobal.net
Thu Jul 13 03:05:57 EDT 2006
I find the stones listed in the Catalogue of Meteorites
as "pseudometeorites" to be sometimes of interest.
Bleckenstad (Sweden) is discussed in this List Posting
from 2003, where three cases of sedimentary meteorites
are thrown up by yours truly:
Then, there's a French fall from 1900 -- Langeac. The stone
was thrown away after being examined in 1927. It looked like
a meteorite but it was basalt, and of course (1927, remember),
there are no basalt meteorites! Did they throw a big Martian
look-alike to DAG 476 ($1275/gm) in the trash?!
The issue is all in the recognition department, and the trouble
department. Nininger found a sedimentary meteorite while
searching for Pasamonte and just put it in a drawer, it is reported...
Who needs that kind of trouble? Remember Nininger's copper
"meteorite"? He did. (It appears that it was a melted bearing from
an aircraft in trouble, but the witness was nearly hit by it, so
Nininger took it seriously and it took him a long time to
resolve the origin. Anomalous meteorites are a headache.)
How to recognize a meteorite from Mercury:
We should have Mercurian meteorites, about 1/15th of the
number of Martian meteorites, which number is getting high
enough that I hope for some unequivocal case to occur, not
the usual "maybe's."
A sedimentary meteorite could just as well be a chunk of
Earthly ejecta blasted off the planet into a co-orbit and eventually
re-captured and come back as a meteorite after 100,000 or
a million years. Bret Gladman's simulations show this happening
with a reasonable frequency, comparable to Martian meteorites
arriving on our doorstep. Where are they?
And then, how would you recognize a meteorite from Venus?
Two centuries ago, the scientists of the day sneered at the
ignorant peasants that asserted that stones fell from the sky. I
worry that today some of the "knowledgeable" would just
toss a sedimentary meteorite in the trash can... just like
Ashley and Delaney. Why don't they, or somebody, try to
find out what happened to Bleckenstad and other "sedimentary"
pseudometeorites, or is that trash can too deep? Or are they
still in some dusty storage drawer of museums that found them
long ago an embarassment?
Sterling K. Webb