gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1970.037.290.07 Application of the Muscovite-paragonite Geothermometer to a Staurolite-grade Schist from Sulitjelma, North Norway Henley K. J. 1 Department of Geology, University College, Gower Street, London, W.C. 1

Present address: The Australian Mineral Development Laboratories, Conyngham St., Frewville, South Australia 5063.

 6 1970 37 290 693 704 12 6 1969 Copyright © 1970, The Mineralogical Society 1970 Summary

The occurrence of coexisting paragonite (containing 0·70 % CaO) and muscovite (containing 0·16 % CaO) in a staurolite-grade paragonite-muscovite-hornblende-garnet-biotite schist from Sulitjelma enables an estimate to be made of the temperature of recrystallization, using an extension, based on crystal chemistry considerations and available analyses of muscovites and paragonites from metamorphic rocks, of the experimentally determined solvus in the K-Na white mica system into the Ca-K-Na system. This temperature of recrystallization is approximately 550–70 °C and is consistent with the experimental data on the coexistence of staurolite and quartz in the system Fe-A1-Si-O-H (Richardson, 1968).