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Re: The Strange Mystery of the Albion Meteorite (Iron)

Julia asked:
"should we not put more emphasis on these anomalous irons in discovering
how the asteroids themselves accreted.  If there are vugs, vacuoles and
voids within asteroids (or some) learning to distinguish between them of
course would be critical in any calculations NASA  or any other space
agency may make.


Hello JJ and All,

To quote Buchwald (1975),
"The anomalous classes embrace meteorites which for one reason or another
do not fit into the normal classification; with a negative criterion like
this, individual members must necessarily be very different."

A general assumption is that similar chemical classifications between two
meteorites indicate that the two meteorites came from the same parent body
or asteroid. It is reasonable to think that all H chondrites came from the
same asteroid. All L chondrites came from the same asteroid, as did LL
chondrites. This may be an oversimplification of the situation, but it is
easier to assume that like classes have like sources even though a
reasonable reaction would be to think there are many related asteroids thus
producing similar meteorites but from different parent bodies.

The same assumption is made with iron meteorites. We have samples of at
least 12 distinct iron asteroids because we have 12 distinct iron chemical
classifications. Another step would be to add the total number of known
anomalous irons to the pile raising the number considerably. I do not know
for certain but I believe the total number of anomalous iron meteorites is
around 100 localities. Bernd?

Regarding Julia's question:
"With regard to 12 Classifications of Iron meteorites,  how often are these
reviewed and possibly re-categorized? "

Partsch proposed the first meteorite classification scheme in 1843. There
have been updates to it, notably in 1846, 1863, 1872, 1896, 1920, 1968, and
1971. The review of the classification system is constant, but the one in
use today seems to work quite well. If there are 100 or so anomalous irons
given the many hundreds of specimens which fit nicely into the 12 chemical
classifications, it seems the 12 classes are robust, but definitely not
complete with only about 80-90% of the irons chemically grouped.

Bernd, maybe you can shed more light on this subject.

Sincerely,

Martin
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