Mineralogy of Coexisting Zoisite-Clinozoisite and Epidote from Sakarsanahalli, Kolar, Karnataka
Authors
-
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012
T. R. Narayanan Kutty -
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012
G. V. Anantha Iyer
Abstract
X-ray, infrared spectra and chemical data reveal that the pink mineral from the calc-silicate rocks of Sakarsanahalli, Kolar, is a mixed phase of zoisite and clinozoisite. It is generally cloudy due to fine inclusions of plagioclase. Polymorphic transformation relations could be observed in it. The mixed crystals are found to be stable when the replacement of Al by Fe3+ is less than 10 atom per cent. The yellow-green to green mineral, on the other hand, is monophasic epidote, with 30 to 35 atom per cent Al being substituted by Fe3+. Hydrothermal experiments show that zoisite-clinozoisite transforms to zoisite-epidote (iron-rich clinozoisite) pair at higher temperature and pressure. However, larger Fe3+ activity upsets this transformation relation, where the monoclinic epidote phase alone is stabilised.Downloads
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References
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