The dissolution forms of diamond crystals in CaCo3 melt at 7 GPa

For the first time we have experimentally obtained and studied the crystal forms of diamond obtained on its dissolution in CaCO3 melt at 7 GPa and 170 0-1750 degrees C (conditions for synthesis and growth of diamond in the sys tem CaCO3-C). The morphology of these crystals was invesigated in detail, u sing photogoniometry. At 15-20 % loss of the initial mass, the octahedral c rystals transform into trigon-trioctahedroids, and cuboctahedrons are the b asis for formation of tetrahexahedroids in combination with the surfaces of tetragon-trioctahedroids. The data obtained allow a conclusion that the di ssolution form of diamond crystals at intermediate stages depends on the co mposition of solvent and geometry of the initial crystals. Tetrahexahedroid is assumed to be the stationary dissolution form of diamond in CaCo3 melt at experimental parameters.