Experimental Etching of Diamonds: Extrapolation to Impact Diamonds from the Popigai Crater (Russia)

Diamond etching in high-temperature ambient-pressure experiments has been performed aimed to assess possible postimpact effects on diamonds in impact craters, for the case of the Popigai crater in Yakutia (Russia). The experiments with different etchants, including various combinations of silicate m...

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Bibliographic Details
Published in:Minerals (Basel) 2021-11, Vol.11 (11), p.1229
Main Authors: Sonin, Valeri, Zhimulev, Egor, Chepurov, Aleksei, Gryaznov, Ivan, Chepurov, Anatoly, Afanasiev, Valentin, Pokhilenko, Nikolai
Format: Article
Language:English
Subjects:
Craters
crystal morphology
Crystals
Diamonds
Etch pits
Etchants
Etching
etching experiments
Experiments
Gases
Graphite
Graphitization
High temperature
impact diamonds
Inert gases
Martensitic transformations
Melts
Mineralogy
Morphology
Oxidation
Oxidizing agents
Popigai impact crater
Rare gases
Rock
Rocks
Sculpture
Silicates
Striations
surface graphitization
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Summary:Diamond etching in high-temperature ambient-pressure experiments has been performed aimed to assess possible postimpact effects on diamonds in impact craters, for the case of the Popigai crater in Yakutia (Russia). The experiments with different etchants, including various combinations of silicate melts, air, and inert gases, demonstrated the diversity of microstructures on {111} diamond faces: negative or positive trigons, as well as hexagonal, round, or irregularly shaped etch pits and striation. The surface features obtained after etching experiments with kimberlitic diamonds are similar to those observed on natural impact diamonds with some difference due to the origin of the latter as a result of a martensitic transformation of graphite in target rocks. Extrapolated to natural impact diamonds, the experimental results lead to several inferences: (1) Diamond crystals experienced natural oxidation and surface graphitization during the pressure decrease after the impact event, while the molten target rocks remained at high temperatures. (2) Natural etching of diamonds in silicate melts is possible in a large range of oxidation states controlled by O2 diffusion. (3) Impact diamonds near the surface of molten target rocks oxidized at the highest rates, whereas those within the melt were shielded from the oxidizing agents and remained unchanged.
ISSN:2075-163X
2075-163X
DOI:10.3390/min11111229