I was recently reminded, when reviewing manuscripts for journals, of the
striking differences between Anglo/American archaeometallurgists on the one
hand, and German/Swiss/French archaeometallurgists on the other, in the matter
of identification of minerals in slags and ores from archaeological sites. (As
far as archaeometallurgists of other nationalities are concerned, I don't have
enough data to offer an opinion). Although I obviously belong to the
Anglo/American group, it is clear to me that the German/Swiss/French
archaeometallurgists are the more reliable in their mineral identifications.
The reasons for this, I think, is that many of the G/S/F group come to
archaeology from mineralogy or geology, whereas in the A/A world most
archaeometallurgists come to the subject from metallurgy/ materials science, or
(increasingly commonly) have no background in science before enrolling for
training in archaeometallurgy.

One consequence of this difference is that in Anglo-American archeometallurgy
the main technique for investigation of slags and ores is the scanning electron
microscope with energy-dispersive x-ray analysis (EDAX). Obviously this gives
chemical composition, not mineralogical identification. Sometimes this is
combined with XRD for mineral identification, but increasingly rarely. Using
EDAX alone, mineral identification is, in essence, just an informed guess.

Let me give a real example. With iron smelting slags, there is a widespread
tendency in A/A archaeometallurgy to assume that if you get X-ray peaks for
iron and silica, then the phase is fayalite. But there are other
possibilities, namely the iron-rich clinopyroxenes and orthopyroxenes. I'm
particularly puzzled by the fact that in African iron slags I quite often see
orthoferrosilite (identified in thin section by petrographic methods) but that
this has not, to my knowledge, ever been identified in British iron smelting
slags. Is this a real difference between slags in the two areas? Or is
orthopyroxene just not being identified in British slags? (I'm not picking on
the Brits - for obvious reasons I don't have much opportunity to examine iron
slags from the Americas!)

Does it matter? Even though I don't have a German gene in my body, I do side
with the continental archaeometallurgists in thinking that full and accurate
description does matter, even if it has no obvious consequences in term of
technological reconstruction. I think that students working on extractive
metallurgy should be trained in optical crystallography as well as in SEM/EDAX.
Yet very few in A/A archaeometallurgy can use the petrographic microscope
effectively, and even fewer can identify ore minerals in reflected light. These
skills are much more often used in G/S/F archaeometallurgy, and it shows in the
quality of their publications on extractive metallurgy.

Petrographic and ore microscopy may decline in importance as Raman microscopy
becomes more developed - at the moment the limiting factor is the availability
of Raman reference spectra for minerals - and Raman microscopy is certainly
easier to learn to use. But I don't think that it will entirely replace the
optical methods, and I think that we should be pushing students in A/A
archaeometallurgy programs to learn some optical crystallography and become at
least competent, if not expert, in these methods.