The solid state reduction of iron ore in the pre-industrial bloomery produces a metallic iron sponge mixed with slag products, many of which are incorporated as inclusions in the final forged products. Compositional analysis of these non-metallic inclusions by energy-dispersive x-ray analysis can be compared with wet chemical analysis of bulk furnace slags and unreduced ores to yield significant information regarding both the reduction process itself and the level of technology achieved by the smelters. Fingerprinting the compositional relationships between slag inclusions in excavated iron objects and their parent ores is important to the study of provenance and trading patterns of iron artifacts. This investigation compares Ethiopian bloomery iron, a Roman site at Longthorpe, and laboratory reduction of ores. -- AATA