[M-ZZ44] Geology and culture

[MZZ44-P02] Petrographic characteristics of millstones used in Amami-oshima, Tokunoshima and Miyakojima isalnds, Japan

*Norihito Kawamura¹ (1.School of Regional Resource Management, Graduate School, University of Hyogo)

Keywords:millstone, andesite, Iwo-torishima Island, Amami-oshima Island, Tokunoshima Island, Mitakojima Island

The speaker recently presented a preliminary study of the petrographic characteristics of millstones used widely in private homes on Okinawa Is. (Kawamura, 2023). In this presentation, the author shows that the millstones of Okinawa Is. have certain petrological features (porphyritic structure, black to dark gray in color, phenocrysts composed of plagioclase and pyroxene, and a certain range of magnetic susceptibility), and that they are from Iwo-torishima Is., as previously thought. It is clear that andesite from Kume Island, which was pointed out by Oshiro (2020) as a stone material, was not used for the millstone. It is said that such millstones are also used in the Nansei Islands other than Okinawa Is. Therefore, the author compared the results of a survey of millstones from Okinawa Is. (Kawamura, 2023) with the characteristics of millstones used on other islands, and attempted to clarify the distribution range of millstones from Iwotorishima Is. based on petrographic data. This presentation will discuss the results of a survey of millstones stored at museums in Amami-oshima, Tokunoshima and Miyakojima islands.