Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

Abstract

Nepheline syenites occur as a small concordant body within Precambrian amphibolites around Baradangua of Dhenkanal, Orissa, India. The rocks are characterized by presence of microcline, albite, nepheline and biotite with calcite, sphene, apatite and ilmeno-magnetite as accessories. Nepheline :composition indicates a temperature of crystallisation slightly below 700°C and a subsolvus character of the crystallising liquid. Composition of nepheline syenite is discussed in relation to those of coexisting nepheline and potash feldspar.

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