[meteorite-list] Shirokovsky

[Frank Prochaska]

	One other note:  Refractory brick is for high temperature furnaces
and kilns is commonly made from material with a high concentration of
olivine because it is a refractory mineral.  For example, a dunite formation
in the North Cascades in Washington State is mined for this purpose.


Frank Prochaska






-----Original Message-----
From: meteorite-list-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of
bernd.pauli at paulinet.de
Sent: Monday, July 18, 2005 11:02 AM
To: Meteorite-list at meteoritecentral.com
Subject: [meteorite-list] Shirokovsky

Paul kindly wrote/forwarded this:

"Based on the information given I would concur that this is a man-made
material, 
probably derived from a furnace and quite possibly part of a furnace lining,
i.e.
a refractory brick that has been strongly altered by reaction with the
molten con-
tents of the furnace. This is supported by the very iron-rich composition of
the
olivine and the presence of magnesiowustite and magnesioferrite. This
conclusion
is also supported by the reported 'eutectic' nature of the metal-oxide
intergrowth."

Hello Paul and List,

I thought I might throw in some explanatory remarks to make it easier for
everybody
to understand this metallurgist's comments with regard to the Shirokovsky
material:

refractory:

- difficult to fuse, heat-resisting
- capable of enduring high temperature

Allende is known to contain refractory inclusions

wüstite:

- basically FeO (iron oxide) with a cubic structure

ferrite: I think this is basically kamacite

eutectic:

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.

On p. 142, McSween writes this about acapulcoites:

"At temperatures of 950-1,000°C, a specific combination (called
a eutectic mixture) of iron-nickel metal and troilite melted."

Best regards,

Bernd

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