Ti in corundum traces crystal growth in a highly reduced magma.

Aggregates of corundum crystals with skeletal to hopper morphology occur in pyroclastic rocks erupted from Cretaceous basaltic volcanoes on Mt Carmel, N. Israel. The rapid growth of the crystals trapped volumes of the parental AlO-supersaturated melt; phenocrysts of tistarite (TiO) in the trapped melts indicate crystallization at oxygen fugacities 6-7 log units below the Iron-Wüstite buffer (fO = ΔIW - 6 to - 7), induced by fluxes of mantle-derived CH-H fluids.

Immiscible metallic melts in the deep Earth: clues from moissanite (SiC) in volcanic rocks.

The occurrence of moissanite (SiC), as xenocrysts in mantle-derived basaltic and kimberlitic rocks sheds light on the interplay between carbon, hydrogen and oxygen in the lithospheric and sublithospheric mantle. SiC is stable only at ƒ < ΔIW-6, while the lithospheric mantle and related melts commonly are considered to be much more oxidized. SiC grains from both basaltic volcanoclastic rocks and kimberlites contain metallic inclusions whose shapes suggest they were entrapped as melts.

GZ7 and GZ8 - Two Zircon Reference Materials for SIMS U-Pb Geochronology.

Here, we document a detailed characterisation of two zircon gemstones, GZ7 and GZ8. Both stones had the same mass at 19.2 carats (3.