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Relation between cathodoluminescence and trace-element distribution of magmatic topaz from the Ary-Bulak massif, Russia

journal contribution
posted on 2023-05-19, 02:03 authored by Agangi, A, Gucsik, A, Nishido, H, Ninagawa, K, Vadim Kamenetsky
In order to define the cathodoluminescence (CL) properties of magmatic topaz and its relation with trace-element composition, we studied topaz phenocrysts from the Ary-Bulak ongonite massif, Russia using a wide array of analytical techniques. Scanning electron microscopy CL panchromatic images reveal strong variations, which define micrometre-scale euhedral growth textures. Several truncations of these growth textures occur in single grains implying multiple growth and resorption events. The CL spectra of both CL-bright and -dark domains have a major peak in the near-ultraviolet centred at 393 nm. Cathodoluminescence images taken after several minutes of electron bombardment show decreasing emission intensity. Electron microprobe analyses indicate high F concentrations (average OH/(OH + F) = 0.04 calculated by difference, 100 wt.% – total from electron probe microanalyses), consistent with what has been found previously in topaz-bearing granites, and the OH stretching vibration (∼3653 cm−1) was detected in Raman spectra. Laser ablation inductively-coupled plasma mass spectrometry traverses performed across the CL textures detected trace elements at ppm to thousands of ppm levels, including: Fe, Mn, Li, Be, B, P, Nb, Ta, W, Ti, Ga, light rare-earth elements, Th and U. Lithium, W, Nb and Ta appear to be correlated with CL intensity, suggesting a role for some of these elements in the activation of CL in topaz. In contrast, no clear correlation was found between CL intensity and F contents, despite the fact that the replacement of OH for F is known to affect the cell parameters of topaz.

History

Publication title

Mineralogical Magazine

Volume

80

Issue

5

Pagination

881-899

ISSN

0026-461X

Department/School

School of Natural Sciences

Publisher

Mineralogical Society

Place of publication

41 Queens Gate, London, England, Sw7 5Hr

Rights statement

Copyright 2016 The Mineralogical Society

Repository Status

  • Restricted

Socio-economic Objectives

Other mineral resources (excl. energy resources) not elsewhere classified

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