[meteorite-list] Shirokovsky

[bernd.pauli at paulinet.de]

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