TECHNIQUES FOR DETERMINING PRESSURE IN THE HYDROTHERMAL DIAMOND-ANVILCELL - BEHAVIOR AND IDENTIFICATION OF ICE POLYMORPHS (I, III, V, VI)

For H2O densities > 1.0 g/cm(3), a determination of the ice melting te mperature provides the density information required to calculate the P -T path that the sample in a hydrothermal diamond-anvil cell follows w hen the sample is heated isochorically. The principal difficulty is th e identification of the polymorph because of metastable behavior of ic es in the H2O system. Usually, an accurate identification of the liqui dus ice phase can be made without analytical instrumentation and requi res only careful observations.