Ice III
Ice III is a form of solid matter which consists of tetragonal crystalline ice, formed by cooling water down to  at . It is the least dense of the high-pressure water phases, with a density of  (at 350 MPa). It has a very high relative permittivity at 117 and has a density of  (making it more dense than water). The proton-ordered form of  is ice IX. Ordinary water ice is known as ,  (in the Bridgman nomenclature). Different types of ice, from Ice II to Ice XIX, have been created in the laboratory at different temperatures and pressures. See also 
 Ice, for other crystalline forms of ice

References 

Water ice