[meteorite-list] Sikhote-Alin Question

From: star-bits_at_comcast.net <star-bits_at_meteoritecentral.com>
Date: Wed Jun 28 01:14:55 2006
Message-ID: <062820060514.12912.44A2104C0007A4C40000327022070210539C9B070DD39D0E9B9C_at_comcast.net>

Excellent Bernd!! That sounds just like what it is. There is no obvious troilite showing so maybe it was part of the half that split off this piece. Thanks for your always informative posts.

--
Eric Olson
http://www.star-bits.com
<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 Wed 28 Jun 2006 01:14:52 AM PDT