gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1969.037.288.03 Staringite, a New Sn-Ta Mineral from North-Eastern Brazil Burke E. A. J. Institute for Earth Sciences, Free University, Amsterdam Kieft C. Netherlands Organization for the Advancement of Pure Research Felius R. O. Geological and Mineralogical Institute, University of Leiden Adusumilli Maria S. Escola de Geologia, Recife 12 1969 37 288 447 452 12 5 1969 Copyright © 1969, The Mineralogical Society 1969 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.