Morphological Features of Diamond Crystals Dissolved in Fe0.7S0.3 Melt at 4 GPa and 1400°C

An experimental study of the dissolution of natural and synthetic diamonds in a sulfur-bearing iron melt (Fe 0.7 S 0.3 ) with high P–T parameters (4 GPa, 1400°С) was performed. The results demonstrated that under these conditions, octahedral crystals with flat faces and rounded tetrahexahedral diamond crystals are transformed into rounded octahedroids, which have morphological characteristics similar to those of natural diamonds from kimberlite. It was suggested that, taking into account the complex history of individual natural diamond crystals, including the dissolution stages, sulfur-bearing metal melts up to sulfide melts were not only diamond-forming media during the early evolution of the Earth, but also natural solvents of diamond in the mantle environment before the formation of kimberlitic melts.