Preparation of iron rust samples for radiocarbon dating with AMS

It is well known that ages of ancient iron artifacts can be measured by using carbon contained in the iron artifacts. As a simple method of carbon extraction from iron artifacts, a normal quartz tube is used for metal iron combustion at the temperature of 1000℃ for about 15 hrs. We tested the quartz tube method of metal iron combustion successfully for metal iron in fine fragment forms and reported the results previously. In Japan, iron rust samples are commonly excavated from archeological sites of the Kofun period and after. We have tested to collect carbon from iron rust samples successfully by the quartz tube method of iron-rust combustion at 850℃ for 3 hrs. We have experienced that one sample was broken during combustion at 850℃ for 3 hrs. A 14C measurement of only one sample has already been done, but it showed a possibility of a modern carbon contamination in considerable amount during rust process of metal iron.
名古屋大学年代測定総合研究センターシンポジウム報告