Ai. Gorshkov et al., Composition of mineral inclusions and formation of polycrystalline diamondaggregates (Bort) from the Shengli kimberlite pipe, China, GEOCHEM INT, 38(7), 2000, pp. 698-705
The growth features of four diamond aggregates (bort) of the variety VIII f
rom the Shengli kimberlite pipe in China were studied using methods of scan
ning (SEM) and transmission (TEM) electron microscopy. The inclusions of na
tive iron and Fe-Cr intermetallides, sulfides (gersdorffite and siegenite),
lizardite, phlogopite, apatite, barite, and potassic feldspar were found i
n bort and bear significant genetic information. It was demonstrated that m
icrocrystals composing these diamond aggregates show antisceletal faces (1
1 1) and present the transitional growth forms from octahedra to distorted
rhombododecahedra. This fact can indicate a pressure decrease during the cr
ystallization. The formation of the observed assemblages of mineral inclusi
ons was interpreted using the hypothesis of diamond crystallization by inte
raction of deep-source sulfur-bearing reduced fluids with mantle rocks.