山陰地方のニ・三の弥生遺跡に見る管玉石材としての細粒凝灰岩の共通性

The mineral assemblages of host rock of "Kudatama" from Nishikawatsu and Nunoden Yayoi relics in Matsue city, Shimane prefecture, are quite similar to that of Nagase Takahama Yayoi relics in Hawai Cho, Tottori prefecture. The assemblages are characterized by the presence of zeolite, clinoptilolite and anacime. These rocks are greenish homogeneous fine tuff. Na-zeolites such as clinoptilolite and analcime are common as diagenetic alteration products of Cenozoic sediments in Japan.
Neogene strata containing large amounts of volcanic materials as well as marine clastic sediments are distributed in grreen tuff region of Shimane prefecture in Japan. These volcanic materials have been subjected to alteration, including diagenesis and hydrothermal activity. Although zeolites such as clinoptilolite, mordenite, analcime and laumontite are common as alteration minerals in this district, these mineral assemblage are different from host rocks of "Kudatama" from these Yayoi relics.
Therefore fine tuff as host rock of "Kudatama" seem to be bring into this district from other one.