Dear All, 8/05/01
In the context of the most common, "garden variety" rock
types (e.g. metapelites, metaigneous, etc. rocks), I'm interested in
getting a more complete idea of how much Fe3+ chlorite can contain.
I'm aware that in the literature (Deer, Howie, Zussman, the papers by
Foster, etc.) there are analyses of chlorites containing significant
amounts of Fe3+. Some of these chlorites are from veins etc. and so
were probably coarse-grained material. I presume it was possible to
use very pure separates so that the Fe3+ amounts obtained by wet
chemical analyses of such materials are probably quite valid.
However, I'm much less sure this is so for the Fe3+ contents obtained
by wet chemical analyses of chlorites separated from the groundmass
of the common metamorphic rocks. Based on much labor intensive
experience in the past, it seems that not uncommonly, getting a clean
separate of groundmass chlorite, is virtually impossible.
I would appreciate it very much if people can send me any
references to modern attempts to get at Fe3+ in chlorite making use
of instrumental techniques such as Mossbauer (especially,
micro-Mossbauer), Xanes, micro-Xanes, etc. I have a collection of
over 100 reprints on chlorite, but can find very little info therein
on the Fe3+ contents of common, rock-forming, groundmass chlorites.
Many thanks,
Charlie
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