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Morphology and defects of diamond grains in carbonado; clues to carbonado genesis

Vitaly A. Petrovsky, Andrei A. Shiryaev, Vladimir P. Lyutoev, Alexander E. Sukharev and Maximiliano Martins
Morphology and defects of diamond grains in carbonado; clues to carbonado genesis
European Journal of Mineralogy (January 2010) 22 (1): 35-47


The morphology and defects in diamond grains comprising Brazilian carbonado have been investigated using X-ray diffraction, photo- and X-ray luminescence, electron paramagnetic resonance and Raman spectroscopy. Paramagnetic and non-paramagnetic defects in the diamond structure indicate that many of the studied carbonado samples were annealed under mantle conditions, although for a relatively short period of time. Diamond grains show various growth morphological forms with low degrees of dissolution. Individual diamond grains are characterised by a number of important features, such as reentrant apices and incomplete growth layers on faces. We suggest that micron-sized diamond single crystals of predominantly octahedral and cubooctahedral shape grew under conditions of decreasing carbon supersaturation. The temperature decrease serves as a plausible driving force for crystallisation. During the second stage of carbonado formation, mass crystallisation of diamond has occurred. The necessary C supersaturation was likely caused by crystallisation of other minerals, leading to decrease in the volume and/or structure of the parent solution.

ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 22
Serial Issue: 1
Title: Morphology and defects of diamond grains in carbonado; clues to carbonado genesis
Affiliation: Russian Academy of Sciences, Institute of Geology, Komi Science Center, Syktyvkar, Russian Federation
Pages: 35-47
Published: 201001
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 66
Accession Number: 2010-033125
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
S34°00'00" - N05°15'00", W74°00'00" - W34°00'00"
Secondary Affiliation: Russian Academy of Sciences, A. V. Shubnikov Institute of Crystallography, RUS, Russian FederationFederal University of Minas Gerais State, BRA, Brazil
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201019
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