In-situ FE-SEM observation of Fe-oxide crystallization in a magma

Abstract

We conducted in-situ observation of Fe-oxide crystallization using a JEOL JSM-7100F FE-SEM with a Protochips Aduro heating stage. As a starting material we used a pumice clast of Sakurajima 1914 Plinian eruption with almost microlite- and nanolite-free groundmass glass containing 0.5 wt% dissolved H₂O. At 950°C, crystallization by particle attachment and subsequent shape change were observed. The crystallization via non-classical pathways, which have recently been proposed in some solution systems, is presumed to occur in silicate melts.