The solid form of water, although the generic term "ice" is sometimes used to denote the solid phase of any substance. There are 10 known forms of ice. An additional two forms were predicted based on numerical simulations by Benoit et al. (1996) and Svishchev and Kusalik (1996). Ice XI should form at room temperature at a pressure of 300-400 GPa, and should be composed of a distorted hexagonal close-packed lattice. Ice XII should exhibit a quartz-like structure and should form at a pressure of 300-500 MPa in the presence of an electric field.