[meteorite-list] The Classification Of Meteorites

[AL Mitterling]

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"