21-30 ASPECTE PRIVIND COMPOZIŢIA PATINEI UNOR MONEDE ROMANE DE BRONZ


ASPECTS CONCERNING THE COMPOSITION OF SOME
BRONZE ROMAN COINS PATINA
The earlier roman bronze denominations, such as and sestertius, were
stroked in bronze (Cu Sn binary alloy). The coinage title decreases on the later
Roman Empire, silver denarius were finally replaced by the copper follies. The
X-ray diffraction analysis of such coins surface allows us to identify the rust
compounds. We found that on the bronze coins surface are developed mainly
copper oxides, hydroxides as well as tin oxide. We also reach a complex CuSn
hydroxide which gives a greenish yellow shade of the patina. The green hue of
patina is significant enhanced by the average of copper carbonate content also
found as a patina component. The copper foils feature only copper oxides and
hydroxides without carbonates. It proves that the investigated follies laid in a
more inert soil (e.g. quartz sand). The colour of patina is dark brown to shiny
black due to the refined mixture of copper oxides and hydroxide. Some quartz
traces were identified on the coins surfaces as residues of soil. The performed
analysis gives important data useful for modern fake’s identification.
Cuvinte cheie: patină, structură, difracţie cu raze X
Keywords: skate, structure, X-ray diffraction

30 ASPECTE PRIVIND COMPOZIŢIA PATINEI UNOR