Minerals in Volcanic Ash 1: Primary Minerals and Volcanic Glass

Abstract

　Volcanic ash is fragments of magma, and consists of minerals and volcanic glass. These mate-rials in the ash can provide important information on the nature of the magma, because chemical compositions of magma usually show distinct features in each volcano, and because assemblages and compositions of minerals reflect their host melt. Using assemblages and chemical compositions of minerals and glass chemistry, it may be possible to corelate volcanic ash distributed over a wide area. In addition, we may identify the source volcano of the ash. We show several examples of correlating volcanic ash and determining source volcanoes. Moreover, it is possible to discuss magmatic and eruption processes recorded in volcanic ash. We also show several examples of discussing eruption sequences and magma mixing processes using analysis of volcanic ash.