gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1969.037.285.08 Phase Relationships in the Join Ca(OH)2-CaCO3-Ca3(PO4)2-H2O at 1000 Bars Biggar G. M. B.Sc. Ph.D. Grant Institute of Geology, University of Edinburgh 3 1969 37 285 75 82 Copyright © 1969, The Mineralogical Society 1969 Summary

Phase equilibria involving calcite, apatite, portlandite, liquid, and vapour were determined at 1000 bars. Calcite, apatite, and portlandite melt at 654 °C to form a liquid of composition (wt %), Ca(OH)2 53 %, CaCO3 46 %, Ca3(PO4)2 1 %. With water present melting occurs at 635 °C to form a similar liquid with a low water content. The X-ray diffraction patterns of the equilibrium apatites were not significantly different from synthetic hydroxyapatite.