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Intergrowths in ilmenite of the beach sands of Kerala

Published online by Cambridge University Press:  14 March 2018

N. K. Rao
Affiliation:
Atomic Energy Establishment, Trombay, Bombay, India
G. V. U. Rao
Affiliation:
Atomic Energy Establishment, Trombay, Bombay, India

Summary

A detailed study of ilmenite concentrates from Chavara and Manaalakurichi deposits has brought to light several interesting textures traceable to exsolution, eutectic crystallization, and replacement and alteration. Magnetite-ilmenite, magnetite-ilmenite-picotite, ilmenite-picotite, ilmenite-hematite, and ilmenite-rutile exhibit exsolution intergrowths. Part of the ilmenite seems to have been formed either by oxidation of ulvöspinel or from a cubic phase of ilmenite by monotropic inversion. Some of the ilmenite-hematite intergrowths display either an emulsoid or a triangular type of texture. Subgraphic intergrowth is observed between ilmenite-magnetite and ilmenite-rutile, suggesting an eutectic relationship between them.

Magnetite-hematite, magnetite-goethite, and magnetite-maghemite intergrowths are the result of alteration of magnetite. Sphene also partly replaces some ilmenite grains.

The proportion of ilmenite grains with and without intergrowths and the probable origin of the intergrowths and their effect on the marketability of ilmenite concentrates are discussed in the paper.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1965

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