[meteorite-list] Chladnite (Was: Rocks from Space Picture of the Day - August 24, 2010)

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 24 Aug 2010 11:02:36 UT
Message-ID: <DIIE.000000B700004F64_at_paulinet.de>

Hello List,

Richard wrote: "Chladnite? I see this fall is now classified as a
diogenite but could anyone discuss the term Chladnite a bit more?

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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.

Excerpts:

Chladnites

This combination of minerals has been found in only one meteorite, Bishopville.
The stone is coarse grained and consists mostly of friable snow white enstatite.
Rose observed other white grains, but could not identify them. I find these to be
plagioclase. The third constituent is pyrrhotite. The stone's crust has a marbled
appearance, being partly colorless, partly black, white, bluish, and gray.

Enstatite occurs in large and small grains, mostly large. I observed distinct crystal
boundaries on one of the small grains, ...The grains are cut by many fine, irregular
cracks ... Plagioclase is usually attached to the small enstatite grains...Pyrrhotite
forms large and small grains...

The analysis of Rammelsberg (1861), which found Al2O3, CaO, and alkalis in small
amounts, in addition to the ingredients of enstatite, is in full agreement with
the microscopic description just given.

Rose also reports small amounts of nickel-iron and a black mineral that sometimes fills
fine cracks. Breaking the stone along such cracks, I observed a shiny material, similar
to that in meteorites to be described later, in which the veins consist of iron, pyrrho-
tite, and silicate glass...

Diogenites

This class differs little in mineralogy from the preceding one. The main constitutent is
bronzite or hypersthene; these minerals and enstatite are members of the same series.

Therefore the d i s t i n c t i o n between *chladnite* and *diogenite* depends only
on c o n t e n t of f e r r o u s o x i d e.

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Regards,

Bernd
Received on Tue 24 Aug 2010 07:02:36 AM PDT