Microparticles of native metals, sulfides, and oxides in andesitic ashes of Karymskii Volcano

New data on accessory mineral phases found in ashes of the erupting Karymskii Volcano as micro-dispersed particles of native metals (Al, Fe, and Zn), intermetallic compounds, sulfides and oxides of iron, and carbonaceous substances are presented. Dominating submicron particles of native Al and Fe are largely confined to coarse-grained ash fractions; this is supported by extensive observations. The co-occurrence of iron oxide and sulfide particles of the same size possibly indicates extremely heterogeneous conditions of gas transport reactions during the eruption. The presence of native metals and carbonaceous compounds may attest to periods of a highly reducing environment in the fluid system supplying Karymskii Volcano.