Culinary rock salt is actually halite. Its name is derived from the Greek word hals, which means “salt.” Most halite is colorless, white, gray, orange, or brown, but it can also be bright blue or purple. The orange color comes from inclusions of hematite, while the blue and purple colors indicate defects in the crystal structure. Halite is commonly found in massive and bedded aggregates as rock salt. It also occurs in coarse, crystalline masses or in granular and compact forms. Halite crystals are usually cubic. Sometimes, halite may form “hopper” crystals in which the outer edges of the cube faces have grown more rapidly than their centers, leaving cavernous faces. It is widespread in saline evaporite deposits.

Name: From the Greek for salt.

Association: Sylvite, polyhalite, kieserite, carnallite, gypsum, anhydrite, dolomite.

Chemical Properties of Halite

Chemical Classification Halide mineral
Chemical Composition NaCl

Physical Properties of Halite

Color Colorless or white
Streak White
Luster Vitreous
Cleavage Perfect On {001}
Diaphaneity Transparent, Translucent
Mohs Hardness 2½ on Mohs scale
Specific Gravity 2.17
Diagnostic Properties Salty flavor, Fluorescent
Crystal System Cubic
Tenacity Brittle
Fracture Conchoidal
Density 2.168 g/cm3 (Measured)    2.165 g/cm3 (Calculated)

Optical Properties of Halite

Type Isotropic
Color / Pleochroism Weak
Birefringence Isotropic minerals have no birefringence


Halite occurs in significant beds of sedimentary evaporite minerals that result from the drying up of enclosed lakes, playas, and seas. Salt beds can be masses of meters thick and underlie wide regions. In the United States and Canada significant underground beds amplify from the Appalachian basin of western New York through components of Ontario and underneath a lot of the Michigan Basin. Other deposits are in Ohio, Kansas, New Mexico, Nova Scotia and Saskatchewan. The Khewra salt mine is a huge deposit of halite near Islamabad, Pakistan. In the United Kingdom there are three mines; the most important of these is at Winsford in Cheshire generating on common one million tonnes consistent with year.Salt domes are vertical diapirs or pipe-like loads of salt that have been essentially “squeezed up” from underlying salt beds by means of mobilization because of the burden of overlying rock. Salt domes incorporate anhydrite, gypsum, and local sulfur, in addition to halite and sylvite. They are common alongside the Gulf coasts of Texas and Louisiana and are frequently associated with petroleum deposits. Germany, Spain, the Netherlands, Romania and Iran also have salt domes. Salt glaciers exist in arid Iran in which the salt has broken via the floor at high elevation and flows downhill. In all of those cases, halite is stated to be behaving in the manner of a rheid.

Uses Area

  • It is used as a sweetener in meals.
  • Salt water is lower than the freezing point of pure water. Therefore it causes the melt to put salt or salt water on the ice.
  • Used to harden various foods such as bacon and fish.


Of worldwide occurrence. Well-studied deposits include:

  • in Austria, around Hallstadt, Salzburg, and Hall, near Innsbruck, Tirol. From Bex, Vaud, Switzerland.
  • In Germany, from Stassfurt-Leopoldshall, 34 km south of Magdeburg, Saxony-Anhalt.
  • Deposits with large crystals at Wieliczka (Galicia) and Bochnia, Poland. At Girgenti and Racalmuto, Sicily, Italy.
  • In the Salt Range, Punjab, India.
  • In the USA, in the Michigan Basin, underlying Ohio, Michigan, and New York; as numerous salt domes along the Gulf Coast; and in the Permian Basin of Texas and New Mexico; large crystals at the Potash Corporation of America mine, Carlsbad potash district, Eddy Co., New Mexico


  • Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
  • (2019). Handbook of Mineralogy. [online] Available at: [Accessed 4 Mar. 2019].
  • (2019). Halite: Mineral information, data and localities.. Available at: [Accessed. 2019].
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