[meteorite-list] Sikhote-Alin Question

From: bernd.pauli_at_paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: Tue Jun 27 16:38:53 2006
Message-ID: <DIIE.0000002400000270_at_paulinet.de>

Eric wrote:

"Anyone want to take a stab at what it might be.
 I have no good explanations. Here is a link to
 the auction"

<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=3239&item=230002162891>

OK, ... taking a stab at what it might be. If it is NOT one of those
impact-produced surface craters that McHone and M. Killgore describe
in "Impact-produced surface craters on Sikhote-Alin irons" (cp. MAPS
33-4, Supplement, 1998, p. A101), it might be troilite surrounded by
schreibersite + swathing kamacite.

Buchwald wrote about Sikhote-Alin:

"Troilite occurs in minor amounts, mostly associated with the
schreibersite skeleton crystals which in many instances may have
nucleated upon the troilite. The troilite forms 1-10 mm nodules
and lenticular bodies. In most cases it forms the central part
of cm-sized, intricate, lace-like textures where schreibersite
filaments and hieroglyphs radiate from the troilite in structures
that suggest coarse-grained eutectics (+). Similar structures are
present in, e.g., Sao Juliao, Sandia Mountains and S a n t a
L u z i a*."

.., and on p. 1074, Buchwald wrote about Santa Luzia*:

BUCHWALD V.F. (1975) Iron Meteorites (Univ. of
California, 1975, Vol.3, excerpts from p. 1074):

"Not only is the troilite elongated parallel to the present exterior surface,
but the schreibersite-metal eutectics (+) associated with it also appear to
have formed parallel cylinders 10-40 mm in diameter. Later, swathing kamacite
has grown around these cylinders in the solid state to form concentric shells,
5-15 mm thick. Troilite forms the central part of the cylinders, but, since
it pinches and swells irregularly, it may or may not be present in a given
section perpendicular to the cylinders."

(+) McSWEEN H.Y. (1999) Meteorites and Their Parent Planets
Cambridge University Press, Glossary, p. 290): the liquid that
occurs at the lowest temperature in a chemical system.

So, maybe, we are looking at a cross-section of such a cylinder.

Well, probably not quite as interesting as the ongoing discussion
about fraudulent trade practices, but, anyway, ... my stab ;-)


Bernd
Received on Tue 27 Jun 2006 04:38:24 PM PDT