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

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Studies on Tapiolite from Arehalli Pegmatite, Hassan District, Karnataka


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1 Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad - 500 016, India
     

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Tapiolite hosted in lithium-caesium-tantalum (LCT)-type granitic pegmatite, near Arehalli, of Holenarsipur schist belt (HSB), occurs as euhedral crystals within the muscovite books or in association with columbite-tantalite. In this study, compositional and crystallographic characteristics of the tapiolite are presented. The tapiolite is Ta-rich (79.8% Ta2O5) and also Fe-rich (13.1% FeO) with minor amounts of Nb (3.80% Nb2O5) and Mn (0.30% MnO2), and is a Fe-end member of the FeTa2O6-MnTa2O6 series, ferrotapiolite. The tapiolite has very restricted compositional range. Calculated structural formula of the investigated tapiolite is [(Fe0.27 Mn0.66)0.93 (Nb0.45 Ta1.57 Ti0.004 Sn0.03)2.027O6].

The observed unit-cell dimension of studied tapiolite (ao = 4.7582Å and co = 9.2186Å) matches with the value published in the international centre for diffraction data (ICDD) card for tapiolite standard (ao = 4.750 Å, co = 9.205 Å), suggesting that the investigated mineral belongs to the category of ordered tapiolite. Furthermore, crystallographic data also reveal that studied tapiolite has not been affected by chemical substitutions. Restricted composition of tapiolite coupled with minor to trace content of Fe3+, Mn, Sn, Ti, Sc and REEs support this interpretation.


Keywords

Tapiolite, Mineralogy, Pegmatite, Arehalli, Karnataka.
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  • BANERJEE, D.C., RANGNATH, N., MAITHANI, P.B. and JAYARAM, K.M.V. (1987) Rare metal bearing pegmatites in parts of southern Karnataka, India. Jour. Geol. Soc. India, v.30(6), pp.507-513.

  • CERNY, P. (1991) Rare-element granitic pegmatites. 1. Anatomy and internal evolution of pegmatite deposits. Geosci. Can., v.18, pp. 49-67.

  • CLARK, A.M. and FEJER, E.E. (1978) Tapiolite: its chemistry and cell dimensions. Mineral. Mag., v.42, pp.477-480.

  • GAINES, R.V., SKINNER, H.C.W., FOORD, E.E., MASON, B. and ROSENZWEIG, A. (1997) Dana's New Mineralogy, 8th Edition, John Wiley and Sons, Inc. New York, 1819p.

  • KRISHNA, K.V.G. and THIRUPATHI, P.V. (1999) Rare metal and rare earth pegmatites of southern India. Explor. Res. Atomic Minerals, v.12, pp. 133-167.

  • LAHTI, S.I., JOHANSON, B. and VIRKKUNEN, M. (1983) Contributions to the chemistry of tapiolite – mangano-tapiolite, a new mineral. Geol. Soc. Finland.Bull., no.55, pp.101-109.

  • MAITHANI, P.B. (2010) Rare-metal pegmatite bodies with recoverable columbite-tantalite from the Arehalli area, Hassan dist, Karnataka. Explor. Res. Atomic Minerals, v.20, pp.1-11.

  • RADHAKRISHNA, B.P. and VAIDYANADHAN, R. (1994) Geology of Karnataka. Geological Society of India, Bangalore, 298p.

  • SWAMI NATH, J., RAMAKRISHNAN, M. and VISWANATHA, M.N. (1976). Dharwar stratigraphic model and Karnataka craton evolution. Rec. Geol. Surv. India, v.107, pt.2, pp.149-175.

  • TIKOO, B.N., CHAKI, A., SINGH, Y. and VISWANATHAN, S. (2008). Studies on the distribution and behaviour of 25 elements in columbite-tantalite from some rare-metal pegmatite bodies of Jharkhand, Bihar, and Karnataka: A significant milestone in the growth of ore-geochemistry in India. Mem.Geol. Soc. India, no.73, pp.311-324.

  • WISE, M.A. and CERNY, P. (1996) The crystal chemistry of the tapiolite series. Canadian Mineral., v.34, pp.631-647.


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  • Studies on Tapiolite from Arehalli Pegmatite, Hassan District, Karnataka

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Authors

P. B. Maithani
Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad - 500 016, India
Yamuna Singh
Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad - 500 016, India

Abstract


Tapiolite hosted in lithium-caesium-tantalum (LCT)-type granitic pegmatite, near Arehalli, of Holenarsipur schist belt (HSB), occurs as euhedral crystals within the muscovite books or in association with columbite-tantalite. In this study, compositional and crystallographic characteristics of the tapiolite are presented. The tapiolite is Ta-rich (79.8% Ta2O5) and also Fe-rich (13.1% FeO) with minor amounts of Nb (3.80% Nb2O5) and Mn (0.30% MnO2), and is a Fe-end member of the FeTa2O6-MnTa2O6 series, ferrotapiolite. The tapiolite has very restricted compositional range. Calculated structural formula of the investigated tapiolite is [(Fe0.27 Mn0.66)0.93 (Nb0.45 Ta1.57 Ti0.004 Sn0.03)2.027O6].

The observed unit-cell dimension of studied tapiolite (ao = 4.7582Å and co = 9.2186Å) matches with the value published in the international centre for diffraction data (ICDD) card for tapiolite standard (ao = 4.750 Å, co = 9.205 Å), suggesting that the investigated mineral belongs to the category of ordered tapiolite. Furthermore, crystallographic data also reveal that studied tapiolite has not been affected by chemical substitutions. Restricted composition of tapiolite coupled with minor to trace content of Fe3+, Mn, Sn, Ti, Sc and REEs support this interpretation.


Keywords


Tapiolite, Mineralogy, Pegmatite, Arehalli, Karnataka.

References