Rock salt is sodium chloride, a mineral, often called salt or rock salt. Because salt is a physiological necessity in animal life, it was one of the first minerals that early humans sought and exchanged.

In the past, human consumption was the most important and only bulk use of rock salt. And today compared to industrial use, this is only relatively small. Rock salt has become a bulk raw material in the chemical industry. It is a source of sodium and chlorine used in countless products both domestically and industrially.

In large quantities, rock salt is also used in the food processing industry. Seawater contains about 3% dissolved sodium chloride, and people purposefully evaporate seawater to obtain rock salt. But throughout the geological process, seawater evaporated due to natural causes, and rock salt covered vast areas of the earth's surface as a sedimentary rock.

It is the most abundant evaporite that precipitates in seawater, sequentially after gypsum and anhydrite, so gypsum and anhydrite are often found beneath rock salt. In some places the rock salt is impure and interbedded with it are other precipitated minerals, calcite and potassium salts as well as sand and clay.

More than 75 countries mine rock salt in large quantities. If the rock salt layer is not deep underground, dig a shaft to reach the rock salt layer and mine it using underground mining methods. However, there is a simple extraction method that pumps water to the salt layer, then pumps the brine to the surface, and evaporates the brine to extract rock salt. About 1/3 of today's rock salt is extracted by evaporation of seawater in artificial salt ponds (also called salt fields). After seawater is introduced into the salt pond, it is heated and evaporated by the sun until the salt precipitates.

Although the most common Rock salt is a layered deposit, but it is found well cubed and has cubic cleavage. The crystalline habit and salty taste make this mineral easy to identify.