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Dissolution of synthetic diamonds to produce morphologies similar to natural diamonds; an experimental study

E. I. Zhimulev, I. A. Gryaznov, A. A. Chepurov, V. M. Sonin and A. I. Chepurov
Dissolution of synthetic diamonds to produce morphologies similar to natural diamonds; an experimental study
South African Journal of Geology (2023) 126 (4): 529-538

Abstract

The results on dissolution of flat-faced synthetic diamond crystals of octahedral habit in an Fe-Ni-S melt at 4.0 GPa and 1 400 degrees C are presented. It has been established that the resulting diamond morphology is similar to some natural kimberlitic diamonds and follows the particular sequence: flat-faced octahedron - laminar octahedron - trisoctahedroid with parallel striations in the <110> direction ("O1-D1"). Comparing the obtained results with earlier experimental works it is concluded that oxidisation of octahedral diamonds by means of ditrigonal etching layers and formation of tetrahexahedroid form is a result of diamond interaction with the fluidised kimberlite magma. We suggest that formation of octahedral diamonds with trigonal etching layers does not occur in kimberlite magma, and that diamonds of the O1-D1 morphological series avoided natural oxidation in kimberlite magma, but, like flat-faced octahedrons, were enclosed within xenoliths. Most probably, this dissolution process took place in the mantle prior to their capture by kimberlite. The results support an idea that metal-sulphide melts could be considered not only as a growth place for the world's largest Cullinan-like diamonds found in South Africa (CLIPPIR type), but also as a mantle agent producing crystal morphologies typical for common kimberlitic diamonds: it depends upon carbon content in metal-sulphide melt - with supersaturation of the melt, the growth of diamond occurs while at the undersaturation conditions the dissolution begins.


ISSN: 1012-0750
EISSN: 1996-8590
Serial Title: South African Journal of Geology
Serial Volume: 126
Serial Issue: 4
Title: Dissolution of synthetic diamonds to produce morphologies similar to natural diamonds; an experimental study
Affiliation: Russian Academy of Sciences, Siberian Branch, Institute of Geology and Mineralogy, Novosibirsk, Russian Federation
Pages: 529-538
Published: 2023
Text Language: English
Publisher: Bureau for Scientific Publications, Pretoria, South Africa
References: 64
Accession Number: 2024-008056
Categories: Economic geology, geology of nonmetal deposits
Document Type: Serial
Bibliographic Level: Analytic
Country of Publication: South Africa
Secondary Affiliation: GeoRef, Copyright 2024, American Geosciences Institute. Abstract, Copyright, Geological Society of South Africa. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202405
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