FIG. 2. The phase diagram of ice: ^________, measured stable equilibrium lines ; · ­ · ­ · ­ ·, measured metastable lines; ­ ­ ­ ­ ­, extrapolated or estimated stable lines; ·······, extrapolated or estimated metastable lines.
Ice IV is metastable in the region of stability of ice V. The line above Ice IV is the equilibrium line between liquid water and Ice IV. Not shown are Ice Ic, the amorphous phases, and the ordered versions of Ice V and Ive VI.
Ice X exists above 44 GPa.
Temperature in ^oC; pressure in GPa.