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Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 3 (1962), Pagination: 147-156
Abstract
The mineralogy and petrography of certain wollastonite bearing calc-silicate rocks from different localities in Tinnevelly district are described. These rocks occur as layers, lenses and stringers in gneisses. Wollastonite occurs as a general constituent of some of the calc-silicate bands and also near limestone and quartz vein contacts. Thin sections of these rocks displaying reaction textures indicate interaction between minerals and metasomatic changes during regional metamorphism. Detailed optical determinations of wollastonite and other calc-silicate minerals are presented. Wollastonite is abundant; the other minerals are clinopyroxene (Di90 He10), calcite, scapolite (Ma35 Me65), feldspar (chiefly micropertbite), garnet and sphene. Twinning parallel to elongation in wollastonite and zoning in pyroxene and scapolite are noteworthy. The formation of wollastonite may be attributed to high-grade regional metamorphism, and partly to reaction between limestones and intrusive quartz veins.
