Which non-silicate mineral is commonly used as road salt and a water softener?

• A. Halite (NaCl)
• B. Fluorite (CaF)
• C. Calcite (CaCO3)
• D. Gypsum (CaSO4)

Answer: (A)

Halite, which is sodium chloride (NaCl), is the mineral you’re looking for. It’s a non-silicate that dissolves easily in water to form brine, which lowers the freezing point of water and helps melt ice on roads. That same brine is also used to regenerate ion-exchange resins in water softeners, replacing calcium and magnesium with sodium to soften the water. The other minerals listed—calcite (calcium carbonate), gypsum (calcium sulfate), and fluorite (calcium fluoride)—do not provide the sodium-rich brine or the same practical use for road de-icing or water softening, so they aren’t the typical choice for these applications.