Sodium

Sodium is the sixth most common element in the Earth's crust with an estimated abundance of 2.83%. It is the second most abundant element in sea water after chlorine. One point of interest is that, although the abundance of sodium and potassium is approximately equal in crustal rocks, the former is 30 times more abundant in sea water than is the latter. The explanation for this difference lies in the greater solubility of sodium compounds than of potassium compounds.

Sodium never occurs free in nature because it is so active. For all practical purposes, the only compound from which it is prepared commercially is sodium chloride. That compound is so abundant and so inexpensive that there is no economic motivation for selecting another sodium compound for its commercial production.

By far the largest producer of sodium chloride in the world is the United States, where about a quarter of the world's supply is obtained. China, Germany, the United Kingdom, France, India, and members of the former Soviet Union are other major producers of salt. The greatest portion of salt obtained in the United States comes from brine, a term used for any naturally occurring solution of sodium chloride in water. The term includes, but is not restricted to, sea water, subterranean wells, and desert lakes such as the Great Salt Lake and the Dead Sea. The second largest source of sodium chloride in the United States is rock salt. Rock salt is generally obtained from underground mines created by the evaporation and then the burying of ancient seas.