Ice III

Ice III is a tetragonal crystalline ice, formed by cooling water down to 250 K at 300 MPa. It is the least dense of the high-pressure water phases, with a density of 1.16g/cm3 (at 350 MPa). The proton-ordered form of ice III is ice IX.

Ordinary water ice is known as ice Ih, (in the Bridgman nomenclature). Different types of ice, from ice II to ice XIV, have been created in the laboratory at different temperatures and pressures.