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On the Occurrence and Stability of Divalent Chromium in Olivines Included in Diamonds by Roger G. Burns is a Earth and Planetary Sciences article available to read on EtoBox.

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Olivine inclusions in diamonds from kimberlites originating from the deep Upper Mantle contain significant amounts of chromium. It has been suggested that divalent chromium occurs in these olivines. This hypothesis is supported by recent MSssbauer and electronic spectral measurements at high pressures, which demonstrate that pressure-induced reduction takes place in compounds and minerals initially containing Fe 8+, Mn 8+, and Cu 2+ ions. The process is facilitated at high temperatures. Low oxidation states of other metals such as Cr(II) are expected to be stabilized under the very high pressures and elevated temperature conditions in the Mantle. Since Cr 2+ ions are susceptible to the Jahn-Teller effect, they are predicted by crystal field theory to be stabilized in certain distorted coordination sites, such as the olivine M1 site, all three sites of the fl-spinel phase, and the 7-coordinated site of the strontium plumbate structure-type. The Cr 2+ ions in olivines are stabilized in kimberlites intruded into the Crust by the high confining pressures in the diamond inclusions.

Who reads On the Occurrence and Stability of Divalent Chromium in Olivines Included in Diamonds?

Author

Roger G. Burns

Publisher

Springer; Springer-Verlag; Springer Verlag; Springer Science and Business Media LLC; Society for Mining, Metallurgy and Exploration Inc. (ISSN 0010-7999)

Published

1975

Language

EN

Field

Earth and Planetary Sciences (Physical Sciences)