The morphology and real structure of microdiamonds from the Kokchetav Massif metamorphic rocks, kimberlites, and alluvial placers

A comparative study of the morphology and real structure of microdiamonds f rom the metamorphic rocks and alluvial placer of the Kokchetav Massif and f rom the Udachnaya kimberlite pipe and West-Australian alluvial placers has shown that these microdiamonds practically do not differ in the growth mech anisms, dislocation densities, and nitrogen impurity concentrations. In the Kokchetav Massif all morphological types of diamonds from kimberlites are found. The cuboids of diamonds from all types of deposits have a filamentary struc ture and usually contain a central core. The peculiar structure of the cubo ids is explained in the context of the theory of crystal habit stability. T he morphological variety of microdiamonds within a rock sample, the predomi nance of certain morphological types of crystals in rocks, and the inner st ructure and micromorphology of the cuboids allow the conclusion on the low mobility of the fluid phase during the high-pressure metamorphism responsib le for the metamorphogenic-diamond formation.