[meteorite-list] The Classification Of Meteorites

From: AL Mitterling <almitt_at_meteoritecentral.com>
Date: Mon Jul 4 08:48:09 2005
Message-ID: <42C93003.8050000_at_kconline.com>

To All,

There has been a request for information on the classification scheme of
Meteorites. I have a number of sources that tell about this and no doubt
there are websites that may tell a lot more. Anyone that can shed more
light please let me know. Also someone may have a book I don't that
could help out.

Part One.

My sources says that the first attempt to classify meteorites began in
1840's and were based on structural and chemical differences. Keep in
mind that sometimes chemical and geological terms are used to describe
the same thing and complicate or confuse things a bit. One early
scientist was Paul Partsch, the curator of the Vienna collection of
meteorites who first attempted a classification scheme. He separated the
stones from the irons. He separated the Irons into dense, compact, and
some which contained stony material in their structure. The stones were
divided up into normal and anomalous types with the normal being broken
down into magnesium-rich and magnesium poor groups.

Then in the mid 1900th century a Charles U. Shepard attempted to
categorize meteorites using his own classification system. Like Partsch
he had two main categories of stony and iron types. He subdivided the
stony material into trachytic, trappean, and pumice like and the irons
were classified into malleable homogeneous and malleable heterogeneous,
and brittle. Shepard's system however was flawed with the fact that some
of the specimens contained in his collection were not of meteoritic origin.

A third person who worked on a classification system at the same time
Sheperd had was A. Boisse. He had an advantage over Shepard's system by
in the fact he based his specimens on petrographical and density
factors. So he grouped meteorites into stony, iron and uncompacted
material. Stony's were further divided up into magnetic and non-magnetic
types. Boisse's system suffered from the flaws that in that day and age
it was thought that some meteorites left gelatinous matter after the
fall, color rainwater and snow, and powders.

A fourth attempt was made by Carl von Reichenbach in 1859 who had a long
running dispute with the Vienna curator (guess there was meteorite
fights back then too :-) He measured the nickel iron content but noted
that a chemical competition would have been better. He found few
supporters for his system due to his personality and flaws in his system.

Source: Philip M. Bagnal's excellent book "The Meteorite and Tektite
Collector's Handbook"
Received on Mon 04 Jul 2005 08:48:03 AM PDT