3.) After c300, all such presumably authentic dies appear to
be of iron. A solicitation of input here -- is there any known metallurgical
development which might be correlated with this observation (admittedly,quite
tentative)? Lower slag content, which might make engraving more practical?
Less fragile forms of iron being developed? (Admittedly, the absence of iron
dies some two to 2-1/2 millennia ago might be correlated with the greater
likelihood of bronze dies surviving their environment than iron ones.)
Bill,
Your comment is very interesting because as far as I know, around 300 AD there
was not a metallurgical development in iron production, but a radical change in
the coin production in Roman Empire. My research for my PhD (see the other
message) showed that during Gallienu’s reign the silver content dropped
drastically (less than 5%) and the silver amalgam was introduced as a plating
method. During this period quaternary alloys (Cu-Sn-Pb-Ag) replaced the binary
Cu-Ag alloys in coin production. Diocletian in his monetary reform (293/4 AD)
introduced a much bigger coin the nummus or follies (10g compared to 3g of
antoniniani) which was also made off quaternary alloys and had silver plating
layer on its surface. So maybe the iron dies first used in the striking of
these coins.
This scenario is also supported from your publications. During the period I
examined you have found 27 dies but 6 were considered forgeries. Of the rest, 8
were not identifiable because of their very corroded condition, and 5 were
published in the past but presently are unlocatable. Among the few surviving
examples, the dies used for the production of antoniniani (54a, 54h, 55) were
bronze. The dies 54a and 55 probably were set in an iron case. However, the
dies that coined nummi (folles) and other 4th century coins (57, 57a, 58, 58a,
58b, 58c-e, 59, 60) were iron. Specifically, the face of die 58b had been
hardened by carburisation. Most of the dies had truncated cone or pyramid
shape. Nevertheless, die 58 was a hinged pincer die.
--
Constantina Vlachou - Mogire, Ph.D
Numismatic Museum
12 El Venizelou Ave
106 71 Athens
Greece
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