Halides are compounds in which a halogen element, e.g. chlorine, fluorine, iodine, or bromine, is the sole anion. Halides include compounds such as halite (sodium chloride, NaCl). These minerals are relatively soft, weak, and brittle; many of them will dissolve readily in water. Those that are not soluble in water generally crystallize in the isometric crystal system and develop as cubes.
- Chesterman, Charles W. The Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf: New York (1987). p. 425