University of Tasmania
Browse

File(s) under permanent embargo

Brown diamonds from an eclogite xenolith from Udachnaya kimberlite, Yakutia, Russia

journal contribution
posted on 2023-05-18, 04:19 authored by Stepanov, AS, Korsakov, AV, Yuryeva, OP, Nadolinniy, VA, Perraki, M, De Gussem, K, Vandenabeele, P
We have performed petrographic and spectroscopic studies of brown diamonds from an eclogite xenolith from the Udachnaya pipe (Yakutia, Russia). Brown diamonds are randomly intermixed with colorless ones in the rock and often located at the grain boundaries of clinopyroxene and garnet. Brown diamonds can be characterized by a set of defects (H4, N2D and a line at 490.7 nm) which are absent in colorless diamonds. This set of defects is typical for plastically deformed diamonds and indicates that diamonds were likely annealed for a relatively short period after deformation had occurred. Excitation of brown colored zones with a 632.8 nm He–Ne laser produced the typical diamond band plus two additional bands at 1730 cm−1 and 3350 cm−1. These spectral features are not genuine Raman bands, and can be attributed to photoluminescence at ∼710 nm (1.75 eV) and ∼802 nm (1.54 eV). No Raman peak corresponding to graphite was observed in regions of brown coloration. Comparison with previous reports of brown diamonds from eclogites showed our eclogitic sample to have a typical structure without signs of apparent deformation. Two mechanisms with regard to diamond deformation are proposed: deformation of eclogite by external forces followed by subsequent recrystallization of silicates or, alternatively, deformation by local stress arising due to decompression and expansion of silicates during ascent of the xenolith to surface conditions.

History

Publication title

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Volume

80

Pagination

41-48

ISSN

1386-1425

Department/School

School of Natural Sciences

Publisher

Pergamon-Elsevier Science Ltd

Place of publication

The Boulevard, Langford Lane, Kidlington, Oxford, England, Ox5 1Gb

Rights statement

Copyright 2011 Elsevier

Repository Status

  • Restricted

Socio-economic Objectives

Diamond exploration

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC