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Ali Khoshroo ¹, T. C. Devaraju ¹

Affiliations
1 Department of Studies in Geology, Karnatak University, Dharwad 580003, IN

Abstract

Clays are localized in their occurrence to the sheared and deeply weathered rhyolite-rhyodacite). These contain illite in association with minor proportion of neoforrned chlorite and a large proportion of relic quartz. XRD, IR and thermal properties of Mujjur illite correspond to pure illite. The clays are characterized by higher alkalies (K₂0 4.7%), with correspondingly low PCE value of 1420°C, absence of swelling minerals and very low CEC and dye adsorption.

Keywords

Mineralogy, Economic Geology, Non-Metals, Gadag, Karnataka.

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T. C. Devaraju ¹, Ali Khoshroo ², A. G. UGARKAR ¹

Affiliations
1 Department of Studies in Geology, Karnatak University, Dharwad 580003, IN
2 Aerodynamic Research Center, P.O. Box 19584/449, Tehran, IR

Abstract

A dozen clay deposits occurring in the districts of Belgaum, Dharwad and Chitradurga of Karnataka State have been studied. ln Dharwad district, while the clay deposits derived from greywackes/phyllites are dominated by kaolinite, those derived from the acid metavolcanics contain illite as the sole clay mineral. In Belgaum and Chitradurgadistricts the deposits are kaolinitic, characterised by poor crystallinity and near absence of illite.

Chemically, the clay deposits studied have relatively high silica and low titania. The transformation of precursor rocks to clay deposits which was brought about by insitu chemical weathering and subsequent reworking of the weathered products under tropical climatic conditions was accompanied by enrichment of Al, Zr and Cr and removal of Sit Fe. Ni, Cu and Zn. Presence of relicts of nearly all the major and accessory minerals native to the precursor rocks, in all the litho-units of clay profiles is in agreement with such an interpretation.

Keywords

Economic Geology, Clay, Geochemistry, Mineralogy Chitradurga, Dharwad, Belgaum, Karnataka.

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