Dear Dan,
Antimony appears as an important element in copper and copper alloys on
a number of horizons in prehistory. In general it seems that
copper-antimony binary alloys are unusual, at least in my experience;
the only time I think I have seen antimony as the sole impurity in
bronze above trace levels was in an alleged grave group from the Warring
States period in China, where in fakes made from an otherwise clean
leaded bron ze the antimony came in with the lead because scrap battery
plates or a similar alloy had been used.
In the Nahal Mishmar hoard already cited in this discussion there is
also aresenic. Cu-As-Sb compositions with percentage levels of antimony
are quite common in areas ranging from the Irish Chalcolithic to
prehistoric Bactria, but usually arsenic is the dominant element of the
two. This is not so in central/Alpine Europe in the Early Bronze Age (Bz
A) where coppers smelted from fahlerz ores have very significant
antimony contents, up to several percent in Swiss Salez type axes. These
contain some nickel and silver, the nickel I suspect aiding the
ductility of the alloy (not necessarily a bronze as tin can be low or
absent).
In the Middle Bronze Age in much of northern and western Europe there is
a switch back to pyritic ores but with the beginning of the late Bronze
Age (Ha A2 in central European chronology, LBA 1 in Britain, BF II in
France and Montelius IV in Scandinavia) fahlerz is again very important.
In central Switzerland in about Ha B2 (see publication of Zug-Sumpf)
there was for some reason a shortage of tin and antimony-rich copper was
substituted, with an inverse correlation between tin and antimony, and
antimony up to 8%. This metal was used for a variety of object types.
In prehistory the last occurrences of copper with high antimony contents
for several hundred years are in ingot material of the beginning of the
Iron Age in eastern Switzerland, the Ticino and Slovenia. In the last
named some very complex Cu-As-Sb-Ni compositions are found, and have
been published extensively. There are later occurences, for example in
medieval Britain, but these are for cast vessels of low quality.
In Luristan when bronze was established antimony seems to be a modest
impurity.
Peter
--
Dr Peter Northover,
Materials Science-Based Archaeology Group,
Department of Materials, University of Oxford
Tel +44 (0)1865 283721; Fax +44 (0)1865 841943 Mobile +44 (0)7785 501745
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