1993 Volume 88 Issue 3 Pages 114-120
Volcanic ash from 1992 eruption of Shinmoe-dake was investigated. Smectite and gypsum are present besides feldspar, pyroxenes, hornblende and cristobalite. An energy dispersive X-ray analysis indicates that the smectite is a Fe-rich smectite. The smectite resulted from rock alteration by a geothermal system within the cone at relatively low temperatures before the eruption.