Petrology of smithing slag

Slags are waste formed during metallurgical processes. These artificial silicates materials are similar to rocks. Their composition reflects the raw materials involved and technical practices (raw iron, fuel, addition).

The mineralogy and the texture provide essential information on the physical conditions of the process (temperature, oxygen fugacity). A large panel of mineralogical and geochemical methods are used to characterize these materials. The study of the slag pieces recovered from an archaeological site allows to reconstruct qualitatively and quantitatively the past metallurgical activities.

The aim of the study is to compare more than 600 samples from different archeological site in Switzerland with geochemistry and petrology. This synthetic approach will be the tool for the identification of long term trends and major changes in the iron working technology. The source and behavior of key chemical elements will be investigated to characterize the variability of raw materials and processes involved.