Staringite, a New Sn-Ta Mineral from North-Eastern Brazil

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

Mineralogical Magazine; December 1969 v. 37; no. 288; p. 447-452; DOI: 10.1180/minmag.1969.037.288.03
© 1969, The Mineralogical Society
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