It occurs as the mineral halite (rock salt) and in natural brines and sea water. It has the interesting property of a solubility in water that changes very little with temperature. It is used industrially as the starting point for a range of sodium-based products (e.g. Solvay process for Na2CO3, Castner-Kellner process for NaOH), and is known universally as a preservative and seasoner of foods.
