R1: Characterization and description of minerals (Joint Session with The Gemmological Society of Japan)

[R1P-08] Cuprospinel and cuprorivaite from Aogashima island, Tokyo, Japan

*Daisuke Nishio-Hamane¹, Yoshiya Ohki, Shunsuke Ohsumi (1. ISSP, Univ. of Tokyo)

Keywords:cuprospinel, cuprorivaite, Aogashima Island

Cuprospinel and cuprorivaite were found from Yuhama area, the Aogashima Island, Tokyo, Japan. They occur in fissures and cavities of andesite scoria as the volcanic sublimates. Cuprospinel occurs as black spherical aggregates that exhibit metallic luster. Cuprorivaite occurs as blue plate-like crystals. Chemical composition and unit cell parameters are reported for both minerals. Our cuprospinel was tetragonal, so it was either formed at a high temperature and then slowly cooled, or crystallized at less than 760°C. The forming temperature is under investigation.