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Staringite, a new Sn–Ta mineral from north-eastern Brazil

Published online by Cambridge University Press:  05 July 2018

E. A. J. Burke
Affiliation:
Institute for Earth Sciences, Free University, Amsterdam
C. Kieft
Affiliation:
Netherlands Organization for the Advancement of Pure Research
R. O. Felius
Affiliation:
Geological and Mineralogical Institute, University of Leiden
Maria S. Adusumilli
Affiliation:
Escola de Geologia, Recife

Summary

Staringite, (Fe,Mn)0·5(Sn,Ti)4·5(Ta,Nb)1·0O12, occurs as inclusions in tapiolite from pegmatites at Seridózinho and Pedra Lavreda, Paraiba State, NE. Brazil. An indexed powder pattern is presented. The mineral is tetragonal with a 4·742 Å and c 9·535 Å, and most probably has a ‘trirutile’ structure. Electron-microprobe analysis yielded Ta2O5 21·5%, Nb2O5 1·8, SnO2 73·3, TiO2 0·03, FeO 3·7, MnO 0·3, sum 100·6%. Dcalc 7·17. Micro-indentation hardness (load 100 g) 1033–1187 kg/mm2; reflectivity at 470 nm (R0) 12·8 to (R′e) 14·5%, at 546 nm 12·1–13·9, at 589 nm 12·0–13·7, and at 650 nm 11·8–13·6; staringite is uniaxial positive.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1969

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