A small ice crystal of the hexagonal tabular form; the distance across the crystal from one side of the hexagon to the opposite side may be as large as about 1 millimeter, and the thickness perpendicular to this dimension is of the order of one-tenth as great; this crystal form is usually formed at temperatures of -10 to -20°C by sublimation; at higher temperatures the apices of the hexagon grow out and develop dendritic forms.