Mineralogical and Chemical Characterization of Roman Slag from the Archaeological Site of Castra (Ajdovščina, Slovenia)

This study deals with the mineralogical and chemical characterization of archaeometallurgical material from the Roman archaeological site of Castra (Ajdovscina, western Slovenia). Samples were initially analysed via optical microscopy and X-ray powder diffraction, with the composition of individual phases then determined using scanning electron microscopy coupled with electron-dispersive spectroscopy, and Raman microspectroscopy. Chemical investigation was carried out by using inductively coupled plasma atomic emission spectroscopy to measure the major element content. The results showed that the slag originated from iron smithing operations, with calcium-rich olivines, as well as wuestite and leucite, the most abundant phases. The investigated slags were also found to be characterized by significantly high lime levels, which probably promoted the formation of the calcium-rich olivines.