SiC in Diamond and Kimberlites: Implications for Nucleation and Growth of Diamond

Abstract

Dusty inclusions in diamonds from Fuxian, China contain an assemblage of moissanite (α-SiC) + β-SiC + quartz. Diamondiferous kimberlite from Kimberley, South Africa contains SiC microcrysts with rutile-bearing melt-inclusion tubes and deformation lamellae. They are blue or turquoise-green α-SiC (hexagonal) and the major difference between them is their Al content: 0.2 wt% in the blue and 100 ppm in the green variety. These findings suggest a possible genetic link between SiC and diamond. We propose a mechanism for heteroepitaxial nucleation and growth of diamond on cubic β-SiC substrates, mimicking interpenetrant twinning on {112}, which might provide a smooth, orderly transition from substrate to overgrowth. This growth mechanism may be effective in nature and should be of interest to material scientists who synthesize diamond thin films for industrial purposes.