[meteorite-list] The Classification Of Meteorites (Part Two)

[AL Mitterling]

To all,

The best attempt to classify meteorites was made by Gustav Rose at the 
University of Berlin between the years of 1863 and 1864. He categorized 
specimens by employing mineralogical criteria and much of the 
terminology which he introduced is still in use today. He also divided 
meteorites into stonies and irons. The irons were sub-divided up into
almost pure nickle-iron, pallasites (nickle-iron plus olivine), 
mesosiderites (nickle-iron plus iron oxide, olivine, and augite), he 
went on to divide the stony meteorites into seven categories, 
chondrites, howardites, chassignites, chladnites, shalkites, eucrites, 
and carbonaceous chondrites. Probably one of the most respected 
knowledgeable people of his time, having been a student of meteorites 
for 40 some years, he also help introduce the terms, schreibersite, 
troilite, and Neumann Lines.

In 1872 Gustav Tschermak modified Rose's meteorite classification and 
incorporated the newly discovered facts of the nature of bronzite and 
enstatite in the orthopyroxene solid-solution series. He again refined 
the system in 1883. Tschermak's five category were: 1. irons, 2. irons 
with silicates inclusions, 3. chondritic-textured stones with 
olivine,bronzite,and some iron, 4. olivine, bronzite, or pyroxene 
meteorites, and 5. augite, bronzite and lime feldspar meteorites with 
shining crusts. The Irons were sub-divided into octahedrites showing 
Widmanstatten Patterns, hexahedrites showing the Neumann Lines, and 
ataxites that had no discernible structure.

He noted and observed the band widths in the Widmanstatten Patterns 
varied and so he divided those up into sub classes of (Of) fine, (Om) 
medium, (Og) coarse, and (Ok) curvilinear. Noting the differences in his 
second main category he sub divided up the pallasites (olivine set in 
iron) and mesosiderites (bronzite and olivine in iron) Tschermak's 
chondrite group was broadly similar to Rose's but included 9 
sub-divisions based on the color and texture of specimens. The names of 
the chladnites and chassignites were adopted but later he changed the 
name of the shalkites ot diogenites. Tschermak's final classification 
scheme included Rose's eucrites and howardites.


Source: Philip M. Bagnall's excellent book "The Meteorite and Tektite 
Collector's Handbook"