Certain astrophysically interesting properties of ice grains depend upon their crystallinity. Lower temperatures such as those in the outer layers of a dust cloud favor amorphous ice, the center of the cloud may favor crystalline ice. Amorphous grains have different binding energies than crystalline grains resulting in different evaporation rates and affecting the distance from the sun at which dust is released in cometary tails. They have also different sticking and accommodation coefficients which affect the formation of H2 and of other molecules on their surfaces. In contrast to crystalline grains, amorphous grains can be easily ionized by the stellar ultraviolet photons with important consequences for surface reactions, heating, etc.