Abstract

A 27-element emission spectrographic analysis of “inclusion-free” fragments of an 0.885 carat type II colorless Arkansas diamond, previously crushed for a mass spectrographic analysis of occluded gas, showed detectable traces of Na, Ca, A1 and Si. XRD and chemical analyses of a thin (<2/μm), lustrous, black, opaque, totally-enclosed inclusion lying on (111) of the same diamond showed it to be amorphous and, in decreasing order of abundance, heterogeneously composed mainly of C, Fe, S, and Ni. It is speculated that the black material represents epigenetic carbonization of diamond on (111) by included gas and decomposition products of iron sulfide and iron nickel sulfide inclusions.

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