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

From: AL Mitterling <almitt_at_meteoritecentral.com>
Date: Mon Jul 4 09:41:12 2005
Message-ID: <42C93C73.20503_at_kconline.com>

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"
Received on Mon 04 Jul 2005 09:41:07 AM PDT