Dynamics of Oxidation of a Fe 2+ -Bearing Aluminosilicate (Basaltic) Melt

Abstract
Rutherford backscattering spectroscopy (RBS) and microscopy demonstrate that the ∼1400°C oxidation of levitated droplets of a natural Fe 2+ -bearing aluminosilicate (basalt) melt occurs by chemical diffusion of Fe 2+ and Ca 2+ to the free surface of the droplet; internal oxidation of the melt results from the required counterflux of electron holes. Diffusion of an oxygen species is not required. Oxidation causes the droplets to go subsolidus; magnetite (Fe 3 O 4 ) forms at the oxidation-solidification front with a morphology suggestive of a Liesegang-band nucleation process.