3D micro X-ray spectroscopic analysis of natural diamond formed in ultra-deep underground

A research group led by Professor L. Vincze (Ghent University, Belgium) has recently reported the interesting analysis of 1-20 μm sized inclusions in natural diamond crystals from Rio Soriso (Juina area, Mato Grosso State, Brazil). The crystals are called ultra-deep diamond, because they were formed in the astenospheric upper mantle, the transition zone (410-670 km), and even the lower mantle (>670 km) of the Earth. The experiment is basically 3D imaging by confocal X-ray fluorescence suing synchrotron radiation. By scanning X-ray energy near the Mn and Fe K absorption edges, the authors obtained chemical information on the inclusion cloud in the crystal. It was found that the observed Fe-rich inclusions were ferropericlase (Fe,Mg)O, hematite and a mixture of these two minerals. Another finding was that significant overprint of inclusions along pre-existing planar features is possible without changing their outer shape. For more information, see the paper, "Three-Dimensional Fe Speciation of an Inclusion Cloud within an Ultradeep Diamond by Confocal μ-X-ray Absorption Near Edge Structure: Evidence for Late Stage Overprint", G. Silversmit et al., Anal. Chem., Article ASAP (DOI: 10.1021/ac201073s Publication Date (Web): June 27, 2011).