[meteorite-list] Meteorite find statistics

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 09:43:32 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C8698E5553_at_US-Torrance.mail.saic.com>

Hi All,

I've been following the tektite exchanges (tomes?) with interest,
and hope to have something to add in the near future.

'Til then, I thought I'd post some numbers that I found interesting
having to do with the statistics of meteorite find types. Curious
about how often I could expect a new meteorite find to be a
non-chondrite, I consulted the wondrous "Midnight Blue" Catalogue
of Meteorites to compare the number of falls vs. finds for the
various meteorite types. (Granted, with all the new finds coming
out of northwest Africa, the statistics aren't completely up-to-date,
but they should still be fairly representative.)

As you might expect, in terms of broad meteorite classification
categories, achondrites have the lowest ratio of finds to falls.
More than 1 in 8 achondrites is a fall, compared to 1 in 22 of
the H-chondrites. I guess the old weathered eucrites and howardites
and diogenites and even shergottites don't exactly stand out like
sore thumbs.

Listed below are the numbers of falls and total meteorites by
type, along with the fall-to-total ratio expressed as a
percentage. I've listed them in increasing order of fall-to-
total ratio:

Type Falls Total Fall %
---------- ----- ----- ------
H 316 6962 4.54
Iron 48 865 5.55
L 350 6213 5.63
CC 36 561 6.42
LL 72 1048 6.87
E 15 201 7.46
Stony-iron 12 116 10.34!?
Achondrite 78 610 12.79

I found it interesting that irons weren't #1. I guess the longer
terrestrial lifetimes of chondrites may partly explain this.

The stony-iron ranking was a little surprising: more than
1 in 10 of the stony-irons is a fall! Granted, the number
of stony-iron data points is much smaller than the other
categories, so there is greater statistical uncertainty.

Another thing I noticed is that according to these stats,
LL-chondrites are 50% more difficult to recognize than
H-chondrites. Is the weaker magnetism to blame? Given the
relative ranking of E-chondrites, that would seem to be a
pretty weak argument.

Anyway, I was interested in any ideas you all might have...

Cheers,
Rob
Received on Tue 17 Jul 2001 06:56:04 PM PDT