Non-destructive analyses of iron artifact excavated from Motodaka Yuminoki archaeological site

Mitsui, Seiichiro  

An ancient iron plowshare (ca 1,700 year old) was excavated from Motodaka Yuminoki archaeological site in Tottori Prefecture. We analysed corrosion state with a X-ray CT and corrosion products with a portable XRD/XRF. For comparison, we also analysed iron knife excavated from Miyadani ancient tomb No. 26 and iron adze excavated from Yoshida Nakamichi archaeological site. As results of analyses of the plowshare and the adze, we identified siderite as a corrosion product and confirmed the existence of metal iron in the artifacts. Previous experimental study suggested inhibition of corrosion reaction associated with siderite formation. Good state of preservation of the plowshare and the adze could be attributed to the formation of siderite on the surface of the artifacts.