1. Geological Laboratory Ibaraki Nature Museum Bando Ibaraki Japan
2. Graduate School of Science and Engineering Ibaraki University Mito Ibaraki Japan
3. Department of Natural Sciences, Faculty of Science and Engineering Tokyo City University Setagaya Tokyo Japan
4. Faculty of Science Tohoku University Sendai Miyagi Japan
5. Department of Earth Science, Graduate School of Science and Engineering Ibaraki University Mito Ibaraki Japan