[log in to unmask] wrote:
> What a lot of people tend to forget, is that chemical analyses, lead
> isotope analyses, etc. only really give you a probability of where
> something is from GIVEN you have an adequate sample from all possible
> sources. This is a point that has been stressed in a lot of Pernicka's
> lead isotope work and recently re-iterated (but for basalts and obsidians)
> in Shackley's "Gamma Rays, X-Rays and Stone Tools", JAS 1998:259. As
> Bernie Knapp said somewhere in print, all these chemical characterization
> techniques usually just tell us where it is not from!
Mark,
Yes, as they say "if wishes were fishes we'd all cast a line". I
remember staring at the computer screen fifteen years ago at the peaks
and valleys of a scanning electron microscope analysis of the Euboian
coins I was working on, seeing how similar each coin was of each type,
and wishing that somehow it could all mean something... All I found
that was significant was the hint of an electron shell of zirconium in
the tiny crystals synthesized in a "huge" crater caused by an earlier
spectrum analysis! I felt like I was exploring a vast lunar landscape.
I am finding some interesting sampling errors in Celtic coins,
however. Katherine Gruel's neutron activation analysis of coins in the
Trebry hoard seemed to give a very tiny and gradual debasement of the
coins by amounts that I found very difficult to believe the Celts were
capable of. Figures of 2% seemed unlikely for people who dealt mainly
in divisions of three or four.
When I did a cluster analysis plotted against the chronology, I found
that the moneyers were starting out diligently when mixing the alloy,
but later became rather sloppy in their work. They appeared to have
tried compensating for their errors when they saw the alloy was
shifting too much. The bulk of the errors were in coins with too low a
silver content, but there were also coins with too much silver. The
obviously richer coins could have later been culled out to profit on
the metal (a large number of coins from Le Catillon had been
test-cut). The resulting averages in the surviving specimens shows a
steady decrease over time by a tiny percentage.
It does seem to suggest that the moneyers were given pre-weighed
amounts of copper and silver, and told to make X number of coins. On
one occasion, a low silver/high tin combination made me wonder if a
few scrap potin coins had crept into the silver mix -- these might
have been treated to show a more silver appearance. Colin Haselgrove
once told me that he suspected a similar treatment with sea water to
create a silvery appearance in some Coriosolite coins found in London.
Gruel did, however, identify a real devaluation somewhere near the
outset of Class IV, but this was by a reduction of 25% -- a realistic
figure for the technology of the time.
I'm starting to look into the technology that created British L
staters, and then down to the time of Cunobelin, as I stated in an
earlier email. So far, it seems that the increase in copper was the
only significant change, but who knows what else might be revealed?
> The interaction/lack of interaction between archaeologists, archaeo-
> metrists, and hard scientists would be a whole discussion unto itself.
We need more renaissance men (and women).
Cheers,
John
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