Final answer:
Rock Salt is classified as the mineral halite, satisfying the definition of a mineral by being a naturally occurring, inorganic solid with a fixed chemical formula NaCl and a crystalline structure.
Step-by-step explanation:
Rock Salt is classified as a mineral because it meets the criteria of being a naturally occurring, inorganic solid with a definite chemical composition and a characteristic crystalline structure.
Specifically, rock salt is the mineral halite, which has the chemical formula NaCl (sodium chloride). Halite forms through the evaporation of aqueous solutions that contain high amounts of salt, leaving behind the crystalline salt as the water evaporates.