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LEAD ISOTOPE ANALYSIS OF ISLAMIC GLAZED POTTERY*Sophie Wolf & Mike Tite (RLAHA, Oxford University) The objective of this pilot study is twofold: Firstly we want to try
to establish whether specific lead ores were being used for glaze production
at a workshop and during a particular period of time or whether any available
lead (potentially from multiple sources) was being used. Secondly the
study aims to identify the source or the various sources of lead that
were used for the production of the glazes. The combination of the results
of this study with archaeological evidence should help to recognise the
extend to which lead was traded over long distances and the trade relationships
between different Islamic countries. The study is based on the assumption, that the lead isotope ratios of
a leaded glaze can be attributed to a known lead source, since these ratios
remain unchanged when used in the production of the lead glaze. The methodology
for lead isotope analysis used here is thermal ionisation mass spectrometry
(TIMS). To attribute the identified groups to a known lead source lead,
isotope ratios of the glazes are compared to ore data on a large database
available at the Isotrace Laboratory in Oxford. The Islamic glazes that have been analysed so far include those coming
from two major ceramic production centres, one at Fustat in Egypt, and
the second at Iznik in Turkey. The pottery dates to between the late 8th
to the early 18th century AD and covers a period of more than 800 years
of nearly continuous production of glazed Islamic ceramics. The results of this study show that the Fustat glazes can not be attributed to a particular lead source. However, for the Lustre wares from Fustat we have observed distinct changes in isotopic composition of the lead glazes between the 8th and 12th century AD. The changes are coherent with the transitions from Fatimid to Ayyubid periods and possibly indicate the use of lead from different ore deposits in each of the two reigns. The Iznik glazes have a relatively homogeneous isotopic composition that can be related to a lead source near Balya in West Turkey. Any further interpretation of the results needs to be complemented by more detailed archaeological data. |
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