Ancient iron production is different from
modern industrial iron production in many aspects. The
archaeological investigation of early
iron production usually depends on the debris in the site to figure out the technology and working process.
Slag, waste of iron-working processes such as
smelting or
smithing, is one of the powerful research objects. After the
iron working process, the iron products were always moved and processed, while slag was left at the working site. The size, shape, chemical composition and
microstructure of slag are related to the iron-working process. In addition, given its resistance to
weathering, slag is usually well preserved in the archaeological site. Therefore, it could provide clues to the iron working technology and process.