When a large halite crystal, NaCl(s), is struck with a hammer, it cleaves evenly, 90° straight edges. When a large calcite crystal, CaCO3(s), is struck with a hammer, it cleaves at a slant angle. A crystal of halite, sodium chloride, does not conduct, but when it is pulverized and dissolved it does conduct. A crystal of calcite, calcium carbonate, when placed in water does not dissolve.
