[meteorite-list] Tschermak and Howardites - Part 2 of 2

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:11 2004
Message-ID: <DIIE.0000004000001DE9_at_paulinet.de>

TSCHERMAK G. (1885) Die mikroskopische Beschaffenheit der Meteoriten
(Stuttgart E. Schweizerbart'sche Verlagshandlung, E. Koch, 23 pp.).

English Translation: The Microscopic Properties of Meteorites, Vol. 4,
No. 6 (Smithsonian Contributions to Astrophysics, Washington, D.C., 1964).

Translation by J.A. Wood and E.M. Wood

Howardites (2)

Occasional small pitch-black grains are undoubtedly chromite. Partsch and Rose have
observed very small amounts of pyrrhotite and metallic iron. The above observations
were made on a specimen of Luotolax which I obtained from Prof. F.J. Wiik, the most
reliable source possible. It is identical with the specimen in the Vienna Hofmuseum.
A comparison of my description with that of Rose indicates that he took to be olivine
the same yellow-green grains that I have identified as augite and bronzite.

A correct estimate of the stone's mineralogy has previously been difficult because,
according to the chemical analysis made by Berzelius, the stone must consist mostly
of olivine. However, this erroneous analysis has been superseded by the analyses of
A.E. Arppe (Rammelsberg, 1870), which are in full agreement with the mineralogical
composition reported above.

A small specimen of Maessing given to me by Dr. C. W. von Guembel is quite similar
to Luotolax. The stone is a tuff, in which crystal fragments and small pieces of very
fine-grained rock are embedded in an earthy groundmass. Among the crystal fragments
are pieces of anorthite having the same appearance and the same inclusions as the
anorthite in Luotolax.

Also as in Luotolax, augite is present in Maessing in brown, yellow, and gray-green
fragments with finely lamellar structure. Bronzite is similar in both howardites;
sometimes this mineral occurs in Maessing in euhedral crystals. Luotolax contains
a few fragments of bronzite in bladed aggregations, such as are common in chondrites.

Small rock fragments of approximately the same type observed in Luotolax are present in
Maessing; these are so fine-grained that bronzite can be identified only locally. Chromite
and pyrrhotite occur in the same manner in Maessing as in Luotolax. This description agrees
with that of von Guembel, except that he identifies the greenish fragments as olivine. It is
also consistent with Schwager's chemical analysis (von Guembel and Schwager, 1878).

According to Rose, the Bialystok meteorite is similar to the howardites already described.
Le Teilleul is listed in the catalogue of the Paris Museum as a howardite; judging from the
specimen in the Vienna Hofmuseum, this is correct.
Received on Mon 05 Apr 2004 11:30:41 AM PDT