[meteorite-list] Re-2: Rocks from Space Picture of the Day - January 06, 2008

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 06 Jan 2008 17:31:18 UT
Message-ID: <DIIE.000000A200002504_at_paulinet.de>

http://www.rocksfromspace.org/January_6_2008.html

Jerry writes:

"What a unique specimen. I understand that there is a lack of
metal and that the chemical composition is primarily MgSiO."

Yep, it is almost pure MgSiO3 and, because of its lack of iron, the fusion crust
is a light brown (near-white) or almost clear glassy (translucent) color.

Jerry asks: "Does this make it crustal material?"

According to the late Robert Hutchison: "The fragmental nature of most aubrites
and the presence of trapped solar wind in some sugggests that they are near-surface
breccias."

Harry McSween: "Some aubrite breccias contain fragments of slowly cooled plutonic
rocks as well as melted clasts that formed by impacts and cooled rapidly near the
surface."

Moni inquires: "Is it slightly magnetic?"

Even though most aubrites [exceptions: Mount Egerton with 21% FeNi metal(!) and Shallowater
with 9% metal] are really metal-poor, they do contain small amounts of nickel-iron so my guess
is that it depends on the sensitivity of the magnet used but the attraction should be extremely
weak - almost zero.

Moni: "a piece of stone looking like this I am not sure I would pick it up."

That's exactly what I thought when I got my specimen from Walter Zeitschel.
I said to myself: "What's that? He must be kidding...that isn't a meteorite!"

Moni: "And is the crust grey?"

NORTON O.R. (1998) Rocks From Space II, p. 204: "A fresh specimen has a gray-
white or light tan crust, a distinguishing characteristic of enstatite achondrites."


Moni also asks: "are there more images available?"

Mike Farmer has a few specimens + pictures => http://www.meteoritehunter.com/

Best wishes,

Bernd



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Received on Sun 06 Jan 2008 12:31:18 PM PST