Dear Xander,
I think that you are not the first one to look into such heavily vitrified
ceramics. It certainly has been done in connection with various metal
smelting installations, including crucible studies (and the interface
between slag melt and vitrified ceramic, and how to tell them apart).
Probably a good deal of this is buried in a number of PhD dissertations.
Similarly, I can imagine that the ceramic / kiln people have seen and done
such material. But in general, I'm not aware of any systematic study of
heavily vitrified ceramic materials from an archaeological context.
What I would expect is that - as long as you have little chemical
interaction among furnace charge and wall material - you will see roughly
the same chemistry in the vitrified material as in the ceramic proper, but
in a different mineralogical assemblage and texture (and of course, without
the volatile components which give rise to the bloating of ceramic on
heat-induced collapse, and with the fluxing input of any fuel ash
component). This very texture now depends on the initial ceramic chemistry,
oxygen fugacity for the iron part in it, cooling rates etc. determining
nucleation and crystal growth, and is thus difficult to generalise. I assume
that many people expected little archaeological information to be found in
this material, and hence didn't study it in detail (or didn't publish at
least).
So what you could do right now is get you a SEM or such, photograph and
analyse your various crystaline phases present, plus the glassy matrix I
assume you have, and discuss textures and compositions with an igneous
petrologist (or similar person). I could guess that you will find some
pyroxenitic or feldspatic crystaline material, maybe also some spinels, and
a lot of glass. If you got your ceramic furnace walls contaminated with the
slag proper, things become more interesting, mineralogically speaking, but
not necessarily more telling in terms of archaeological qustions. However,
the importance of chemical interaction among furnace wall, charge and fuel
ash still needs to be stressed (to repeat what Vincent Serneels I guess
first brought up some years ago, and which Ingo Keesmann and his group
worked on to quite some detail, and which Vincent S. and Peter Crew recently
explored for its archaeometallurgical significance (published in 2000).
Thilo
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|