抄録
The Shimajiri mudstone of the tertiary period was presented as bed rock in the middle and southern part of Okinawa island. It was known having the properties of the marine sediments containing the fossils of shell and foraminifer. It has been reported that white crystal material developed from the Shimajiri mudstone in the middle and southern part of Okinawa island. There were few research about white crystal material. In this study, white crystal material was artificially developed from mudstone, it was discussed on the formative process of that material from mudstone. Mudstones (about 5m in depth) were collected in Uruma and Haebaru cities in the middle and southern part of Okinawa island. Collected mudstones were saturated by 5L water on plastic container. Mudstones saturated by water were set during 10-14 days. After drying a quarter of mudstone, water was put in the container. White crystal material were developed from mudstone according to repeat air dry and wet with water. Water soluble sodium and sulfate ions were higher than other ions in mudstone. Chemical analysis suggested that this Shimajiri mudstones were marine sediments. It is possible that white crystal material were developed from the Shimajiri mudstone according to repeat air dry and wet with water. White crystal material from Shimajir mudstone was indicated clearly that Thenardite (Na_2SO_4) was identified by X-ray diffraction analysis.
