gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1994.058.393.11 Mineralogy Subsilicic Magnesian Potassium-Hastingsite from the Prince Olav Coast, East Antarctica Shiraishi Kazuyuki National Institute of Polar Research, Kaga, Itabashi-ku, Tokyo 173, Japan Oba Takanobu Department of Geosciences, Joetsu University of Education, Joetsu 943, Japan Suzuki Morihisa Department of Geology, Faculty of School Education, Hiroshima University, Hiroshima 734, Japan Ishikawa Ken’ichi Department of Earth Sciences, College of General Education, Tohoku University, Kawauchi, Sendai 980, Japan 12 1994 58 393 621 627 24 5 1993 7 2 1994 Copyright © 1994, The Mineralogical Society 1994 Abstract

Two subsilicic magnesian potassium-hastingsites (4.55 and 4.34 wt.% K2O) and one magnesian potassium-hastingsite occur in calc-silicate pods in well-layered gneisses from the transitional amphibolite- and granulite-facies terrain of a Cambrian metamorphic complex, East Antarctica. Subsilicic magnesian potassium-hastingsite is the most K-rich Ca-amphibole yet reported: (K0.85Na0.11Ca0.02)0.98(Ca1.98Mn0.02)2.00(Mn0.01Mg1.92Fe1.202+Fe1.113+Ti0.13Al0.64)5.0−(Si5.64Al2.36)8O22.48(OH,F,Cl)1.52.

 Keywords subsilicic magnesian potassium-hastingsite amphibole East Antarctica