[meteorite-list] Troilite inclusions

[MexicoDoug at aol.com]

En un mensaje con fecha 01/05/2005 12:13:08 AM Mexico Standard Time,  
MexicoDoug escribe:

"It is much more believable to me that we start out with the elements  
[reactants to form FeS] and then they react at the high temperatures in the  foundry 
planetesimal core.  Thus the troilite very plausibly would be  produced right 
then and there in a 1:1 Fe-S ratio without looking for a more  complicated 
explanation."
 
This statement I made got me to thinking further.  While I strongly  support 
it in response to Zelimir's scenario on "oxidation" and equilibration,  and 
the scenario of in situ troilite production in the planetesimals, it may be  
partially moot since more relevant in the context of the question on how  the 
troilite formed in the first place, I think there actually is a very good  
argument to say that the Troilite formed BEFORE the differentiated  parent body 
(e.g., planetesimal).  This is easy to even support  experimentally, although 
indirectly!!
 
What the esteemed colleagues say or have said/measured on this issue?   Merit 
or part of the story at least?
 
This said, experimentally we simply need to consider the troilite content  of 
the chondrites relative to iron and nickel, considering them as precursors to 
 the planetesimals - the most primative bla bla materials of the solar  
disk....  Yup, just take a simple ratio or two.  If the ratio is  fairly similar 
(and how interesting to see if it is more consistent with a  particular 
chondrite group along with the Fe/Ni ratios for added potential  agreement!!), that 
suggests to me that the miscibility-phase separation model  reigns supreme as 
the hypothesis for the spherical troilite inclusions.   (And I am fairy sold 
that at the high pressure the miscible phase is easy to get  in protoplanet P-T 
situations getting back to the phase diagrams.)
 
Makes one want to go back to graduate school:) or at least show up at the  
Met Soc and Planetary science meetings and get a real technical  education:).
 
Saludos, Doug