An integrated approach to the characterization and dating of furnaces in smelting sites in Macedonia, Greece

Metal production sites are characterized by slag heaps which are often difficult to date due to a general lack of diagnostic pottery. This problem has been countered in recent years by the use of absolute dating techniques. Furnace fragments of severely fired clay, which are usually present in such production sites, represent an ideal material for the dating of metallurgical activity. Yet the studies focusing on the dating of furnace debris are very limited, hence there is a need to better evaluate and date such material. In order to gain absolute dates, thermoluminescence (TL) dating of ceramic refractories from sites in northern Greece has been applied. More precisely the sampled archaeological material consists of ceramic tuyères from two areas, namely Angistro and Katafyto, which were used to direct air into the furnaces and were deposited in the slag heaps shortly after the smelting of iron. In addition, fragments of clay linings used for coating the interior surface of the furnace were also studied. A measurement of their TL dose provides the dating of the actual smelting process and contributes towards establishing a chronology for iron production in northern Greece, which is currently lacking. The samples were found to date within the 16th-18th centuries, a period marked by an increase in pre-industrial Ottoman metallurgy. The tuyères were also analyzed by micro-XRF and examined under stereoscope in order to determine their chemical composition and study their morphology. Results show that coarse fabrics of local clay, tempered with various rock inclusions were used in order to produce fire-resistant refractories to withstand cracking at high temperatures.