gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1985.049.350.10 Apatite Composition and the Fugacities of HF and HCl in Metamorphic Fluids Yardley Bruce W. D. * Department of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ

Present address: Department of Earth Sciences, The University, Leeds LS2 9JT.

 3 1985 49 350 77 79 19 3 1984 Copyright © 1985, The Mineralogical Society 1985 Abstract

Microprobe analyses of the halogen contents of apatites from two samples of amphibolite-facies schist from Connemara, Ireland, have been used to calculate the fugacity ratios fHCl/fH2O and fHF/fH2O using the experimental data of Korzhinskiy. The results imply fugacities for both acids in the range 0.03 to 0.1 bars, but whereas for the lower grade rock fHF > fHCl, the migmatitic sample gives fHF⋍fHCl. An independent estimate of fHF/fH2O from the biotite composition in one sample is in acceptable agreement with the result obtained from apatite.

 Keywords apatite halogens metamorphic fluid schist Connemara Ireland