As the ravages of time rake through my memory...some is coming back to me. The
mineral Plessite is an intermediate mixture of both taenite and kamacite. It
may be the bulk mineral in iron meteorites. I need to find it it is also the
composition of the iron flecks in common chondrites of does that nickel-iron
come in various flavors?
I am remiss for not speaking of plessite more frequently when talking about
kamacite and taenite.
Its name even means filling ( Gr:plythos) It's German name is Fulleisen
Buchwald and Massalski named some varieties(according to Wikipedia):
* acicular plessite/Type I plessite
* black plessite/Type II plessite
* cellular plessite/Type III plessite
* comb plessite
* net plessite
* pearlitic plessite
* spheroidized plessite
My recollections are that schreibersite favors almost exclusively taenite
boundaries( I may be mistaken again) and this is where I got insight into my
private hypothesis that phosphorus is a critical factor in differentiating
taenite from kamacite on the macro level. I suspect(dangerous I know) that the
schreibersite bands/fronts, once developed provide a catalyst zone preferential
for taenite and/or nickel, drawing it through the laminae and stacking it
behind the front. As the taenite builds up the front advances into the plessite
so long as the temperature remains within the phase envelope. Now if I can
find that envelope... I can't begin to theorize how schreibersite accreted to
the band that it does when it does but it seems to have a propensity to do so.
In ataxites schreibersite can form crystals plates instead of bands. Owing to
its yellow brassy color my be mistaken for troilite.
I am throwing this out in case anyone has some journal articles on the subject
or cares to discuss the chemistry. If and when I find the specific of past
research I'll pass that along. For now I want to get the Goldman pdf file and
see what I should already know at my age.
Elton
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