Halite

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Halite
Halit (NaCl) - Kopalnia soli Wieliczka, Polska.jpg
Halite from the Wieliczka salt mine, Małopolskie, Poland
General
Category Halide mineral
Formula
(repeating unit)		NaCl
IMA symbol Hl [1]
Strunz classification 3.AA.20
Crystal system Cubic [2]
Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space group Fm3m
Unit cell a = 5.6404(1) Å;Z = 4
Identification
Formula mass 58.433 g/mol
ColorColorless or white when pure. Impurities produce any color but usually yellow, gray, black, brown, red (Depends on isotopes and purity for various colours) [2]
Crystal habit Predominantly cubes and in massive sedimentary beds, but also granular, fibrous and compact
Cleavage Perfect {001}, three directions cubic
Fracture Conchoidal
Tenacity Brittle
Mohs scale hardness2.0–2.5
Luster Vitreous
Streak White
Diaphaneity Transparent to Translucent
Specific gravity 2.17
Optical propertiesIsotropic
Refractive index n = 1.544
Melting point 800.7 °C
Solubility Water-soluble
Other characteristicsSalty flavor, fluorescent
References [3] [4] [5] [6]

Halite ( /ˈhælaɪt,ˈheɪlaɪt/ HAL-yte, HAY-lyte), [7] [8] [9] commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride (Na Cl). Halite forms isometric crystals. [10] The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on inclusion of other materials, impurities, and structural or isotopic abnormalities in the crystals. [11] It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides, and borates. The name halite is derived from the Ancient Greek word for "salt", ἅλς (háls). [3]

Contents

Occurrence

Halite cubes from the Stassfurt Potash Deposit, Saxony-Anhalt, Germany (size: 6.7 x 1.9 x 1.7 cm) Halite-249324.jpg
Halite cubes from the Stassfurt Potash Deposit, Saxony-Anhalt, Germany (size: 6.7 × 1.9 × 1.7 cm)

Halite dominantly occurs within sedimentary rocks where it has formed from the evaporation of seawater or salty lake water. Vast beds of sedimentary evaporite minerals, including halite, can result from the drying up of enclosed lakes and restricted seas. Such salt beds may be hundreds of meters thick and underlie broad areas. [12] Halite occurs at the surface today in playas in regions where evaporation exceeds precipitation such as in the salt flats of Badwater Basin in Death Valley National Park.

In the United States and Canada, extensive underground beds extend from the Appalachian Basin of western New York through parts of Ontario and under much of the Michigan Basin. Other deposits are in Ohio, Kansas, New Mexico, Nova Scotia and Saskatchewan. Deposits can also be found near Dasol, Pangasinan, Philippines [ citation needed ]. The Khewra salt mine is a massive deposit of halite near Islamabad, Pakistan.

Salt domes are vertical diapirs or pipe-like masses of salt that have been essentially "squeezed up" from underlying salt beds by mobilization due to the weight of the overlying rock. Salt domes contain anhydrite, gypsum, and native sulfur, in addition to halite and sylvite. They are common along the Gulf coasts of Texas and Louisiana and are often associated with petroleum deposits. Germany, Spain, the Netherlands, Denmark, Romania and Iran also have salt domes. [13] Salt glaciers exist in arid Iran where the salt has broken through the surface at high elevation and flows downhill. In these cases, halite is said to be behaving like a rheid.

Unusual, purple, fibrous vein-filling halite is found in France and a few other localities. Halite crystals termed hopper crystals appear to be "skeletons" of the typical cubes, with the edges present and stairstep depressions on, or rather in, each crystal face. In a rapidly crystallizing environment, the edges of the cubes simply grow faster than the centers. Halite crystals form very quickly in some rapidly evaporating lakes resulting in modern artifacts with a coating or encrustation of halite crystals. [14] Halite flowers are rare stalactites of curling fibers of halite that are found in certain arid caves of Australia's Nullarbor Plain. [15] Halite stalactites and encrustations are also reported in the Quincy native copper mine of Hancock, Michigan.

Mining

The world's largest underground salt mine is the Sifto Salt Mine. It produces over 7 million tons of rock salt per year using the room and pillar mining method. It is located half a kilometre under Lake Huron in Ontario, Canada. [16] In the United Kingdom there are three mines; the largest of these is at Winsford in Cheshire, producing, on average, one million tonnes of salt per year.

Uses

Salt is used extensively in cooking as a flavor enhancer, and to cure a wide variety of foods such as bacon and fish. [17] It is frequently used in food preservation methods across various cultures. Larger pieces can be ground in a salt mill or dusted over food from a shaker as finishing salt.

Halite is also often used both residentially and municipally for managing ice. Because brine (a solution of water and salt) has a lower freezing point than pure water, putting salt or saltwater on ice that is below 0 °C (32 °F) will cause it to melt—this effect is called freezing-point depression. It is common for homeowners in cold climates to spread salt on their sidewalks and driveways after a snow storm to melt the ice. It is not necessary to use so much salt that the ice is completely melted; rather, a small amount of salt will weaken the ice so that it can be easily removed by other means. Also, many cities will spread a mixture of sand and salt on roads during and after a snowstorm to improve traction. Using salt brine is more effective than spreading dry salt because moisture is necessary for the freezing-point depression to work and wet salt sticks to the roads better. Otherwise the salt can be wiped away by traffic. [18]

In addition to de-icing, rock salt is occasionally used in agriculture. An example of this would be inducing salt stress to suppress the growth of annual meadow grass in turf production. Other examples involve exposing weeds to salt water to dehydrate and kill them preventing them from affecting other plants. Salt is also used as a household cleaning product. Its coarse nature allows for its use in various cleaning scenarios including grease/oil removal, stain removal, dries out and hardens sticky spills for an easier clean.[ citation needed ]

Some cultures, especially in Africa and Brazil, prefer a wide variety of different rock salts for different dishes. Pure salt is avoided as particular colors of salt indicates the presence of different impurities. Many recipes call for particular kinds of rock salt, and imported pure salt often has impurities added to adapt to local tastes. [19] Historically, salt was used as a form of currency in barter systems and was exclusively controlled by authorities and their appointees. In some ancient civilizations the practice of salting the earth was done to make conquered land of an enemy infertile and inhospitable as an act of domination or spite. One biblical reference to this practice is in Judges 9:45: "he killed the people in it, pulled the wall down and sowed the site with salt." [20]

Polyhalite, a mineral fertilizer, is not an NaCl-polymer, but hydrated sulfate of potassium, calcium and magnesium (K2Ca2Mg-sulfate).

Shotgun shells containing rock salt (instead of metal pellets) are a less lethal deterrent. [21]

See also

Related Research Articles

<span class="mw-page-title-main">Gypsum</span> Soft calcium sulfate mineral

Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk. Gypsum also crystallizes as translucent crystals of selenite. It forms as an evaporite mineral and as a hydration product of anhydrite. The Mohs scale of mineral hardness defines gypsum as hardness value 2 based on scratch hardness comparison.

<span class="mw-page-title-main">Kainite</span> Evaporite mineral

Kainite ( or ) (KMg(SO4)Cl·3H2O) is an evaporite mineral in the class of "Sulfates (selenates, etc.) with additional anions, with H2O" according to the Nickel–Strunz classification. It is a hydrated potassium-magnesium sulfate-chloride, naturally occurring in irregular granular masses or as crystalline coatings in cavities or fissures. This mineral is dull and soft, and is colored white, yellowish, grey, reddish, or blue to violet. Its name is derived from Greek καινος [kainos] ("(hitherto) unknown"), as it was the first mineral discovered that contained both sulfate and chloride as anions. Kainite forms monoclinic crystals.

<span class="mw-page-title-main">Natron</span> Carbonate mineral

Natron is a naturally occurring mixture of sodium carbonate decahydrate (Na2CO3·10H2O, a kind of soda ash) and around 17% sodium bicarbonate (also called baking soda, NaHCO3) along with small quantities of sodium chloride and sodium sulfate. Natron is white to colourless when pure, varying to gray or yellow with impurities. Natron deposits are sometimes found in saline lake beds which arose in arid environments. Throughout history natron has had many practical applications that continue today in the wide range of modern uses of its constituent mineral components.

<span class="mw-page-title-main">Evaporite</span> Water-soluble mineral deposit formed by evaporation from an aqueous solution

An evaporite is a water-soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as ocean deposits, and non-marine, which are found in standing bodies of water such as lakes. Evaporites are considered sedimentary rocks and are formed by chemical sediments.

<span class="mw-page-title-main">Epsomite</span> Sulfate mineral

Epsomite, Epsom salt, or magnesium sulfate heptahydrate, is a hydrous magnesium sulfate mineral with formula MgSO4·7H2O.

<span class="mw-page-title-main">Sylvite</span> Potassium chloride mineral

Sylvite, or sylvine, is potassium chloride (KCl) in natural mineral form. It forms crystals in the isometric system very similar to normal rock salt, halite (NaCl). The two are, in fact, isomorphous. Sylvite is colorless to white with shades of yellow and red due to inclusions. It has a Mohs hardness of 2.5 and a specific gravity of 1.99. It has a refractive index of 1.4903. Sylvite has a salty taste with a distinct bitterness.

<span class="mw-page-title-main">Anhydrite</span> Mineral, anhydrous calcium sulfate

Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium (baryte) and strontium (celestine) sulfates, as might be expected from the chemical formulas. Distinctly developed crystals are somewhat rare, the mineral usually presenting the form of cleavage masses. The Mohs hardness is 3.5, and the specific gravity is 2.9. The color is white, sometimes greyish, bluish, or purple. On the best developed of the three cleavages, the lustre is pearly; on other surfaces it is glassy. When exposed to water, anhydrite readily transforms to the more commonly occurring gypsum, (CaSO4·2H2O) by the absorption of water. This transformation is reversible, with gypsum or calcium sulfate hemihydrate forming anhydrite by heating to around 200 °C (400 °F) under normal atmospheric conditions. Anhydrite is commonly associated with calcite, halite, and sulfides such as galena, chalcopyrite, molybdenite, and pyrite in vein deposits.

<span class="mw-page-title-main">Dolomite (rock)</span> Sedimentary carbonate rock that contains a high percentage of the mineral dolomite

Dolomite (also known as dolomite rock, dolostone or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2. It occurs widely, often in association with limestone and evaporites, though it is less abundant than limestone and rare in Cenozoic rock beds (beds less than about 66 million years in age). One of the first geologists to distinguish dolomite from limestone was Déodat Gratet de Dolomieu, a French mineralogist and geologist after whom it is named. He recognized and described the distinct characteristics of dolomite in the late 18th century, differentiating it from limestone.

<span class="mw-page-title-main">Mirabilite</span> Decahydrated sodium sulfate mineral

Mirabilite, also known as Glauber's salt, is a hydrous sodium sulfate mineral with the chemical formula Na2SO4·10H2O. It is a vitreous, colorless to white monoclinic mineral that forms as an evaporite from sodium sulfate-bearing brines. It is found around saline springs and along saline playa lakes. Associated minerals include gypsum, halite, thenardite, trona, glauberite, and epsomite.

<span class="mw-page-title-main">History of salt</span> Role in human culture

Salt, also referred to as table salt or by its chemical formula NaCl, is an ionic compound made of sodium and chloride ions. All life depends on its chemical properties to survive. It has been used by humans for thousands of years, from food preservation to seasoning. Salt's ability to preserve food was a founding contributor to the development of civilization. It helped eliminate dependence on seasonal availability of food, and made it possible to transport food over large distances. However, salt was often difficult to obtain, so it was a highly valued trade item, and was considered a form of currency by many societies, including Rome. According to Pliny the Elder, Roman soldiers were paid in salt, from which the word salary is derived, although this is disputed by historians. Many salt roads, such as the Via Salaria in Italy, had been established by the Bronze Age.

<span class="mw-page-title-main">Searles Lake</span> Lake in the state of California, United States

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<span class="mw-page-title-main">Polyhalite</span> Sedimentary mineral

Polyhalite is an evaporite mineral, a hydrated sulfate of potassium, calcium and magnesium with formula: K2Ca2Mg(SO4)4·2H2O. Polyhalite crystallizes in the triclinic system, although crystals are very rare. The normal habit is massive to fibrous. It is typically colorless, white to gray, although it may be brick red due to iron oxide inclusions. It has a Mohs hardness of 3.5 and a specific gravity of 2.8. It is used as a fertilizer.

<span class="mw-page-title-main">Carnallite</span> Evaporite mineral

Carnallite (also carnalite) is an evaporite mineral, a hydrated potassium magnesium chloride with formula KCl.MgCl2·6(H2O). It is variably colored yellow to white, reddish, and sometimes colorless or blue. It is usually massive to fibrous with rare pseudohexagonal orthorhombic crystals. The mineral is deliquescent (absorbs moisture from the surrounding air) and specimens must be stored in an airtight container.

<span class="mw-page-title-main">Bristol Lake</span> Lake in United States of America

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The Zechstein is a unit of sedimentary rock layers of Late Permian (Lopingian) age located in the European Permian Basin which stretches from the east coast of England to northern Poland. The name Zechstein was formerly also used as a unit of time in the geologic timescale, but nowadays it is only used for the corresponding sedimentary deposits in Europe.

<span class="mw-page-title-main">Sabkha</span> Salt lake above the tide line, where evaporite deposits accumulate

A sabkha is a predominately coastal, supratidal mudflat or sandflat in which evaporite-saline minerals accumulate as the result of semiarid to arid climate. Sabkhas are gradational between land and intertidal zone within restricted coastal plains just above normal high-tide level. Within a sabkha, evaporite-saline minerals sediments typically accumulate below the surface of mudflats or sandflats. Evaporite-saline minerals, tidal-flood, and aeolian deposits characterize many sabkhas found along modern coastlines. The accepted type locality for a sabkha is at the southern coast of the Persian Gulf, in the United Arab Emirates. Evidence of clastic sabkhas are found in the geological record of many areas, including the UK and Ireland. Sabkha is a phonetic transliteration of the Arabic word sabaka used to describe any form of salt flat, including salt marshes and salt swamps. A sabkha is also known as a sabkhah,sebkha, or coastal sabkha.

<span class="mw-page-title-main">Himalayan salt</span> Rock salt from Pakistan

Himalayan salt is rock salt (halite) mined from the Punjab region of Pakistan. The salt, which often has a pinkish tint due to trace minerals, is primarily used as a food additive to replace refined table salt but is also used for cooking and food presentation, decorative lamps, and spa treatments. The product is often promoted with unsupported claims that it has health benefits.

<span class="mw-page-title-main">Chambersite</span> Manganese borate mineral

Chambersite is a manganese borate mineral with formula Mn3B7O13Cl. It is a member of the borate mineral series that includes other minerals such as ericaite and boracite. When chambersite was first discovered, it was the second chemical analogue of boracite to be found in nature. It was discovered as a mineral at Barber's Hill salt dome in Texas in 1957 and in 1971 at the Dongshuichang deposit in Jixian, Tianjin, China. Chambersite occurs associated with the evaporite minerals halite, anhydrite, and gypsum.

<span class="mw-page-title-main">Leonite</span> Hydrated double sulfate of magnesium and potassium

Leonite is a hydrated double sulfate of magnesium and potassium. It has the formula K2SO4·MgSO4·4H2O. The mineral was named after Leo Strippelmann, who was director of the salt works at Westeregeln in Germany. The mineral is part of the blodite group of hydrated double sulfate minerals.

<span class="mw-page-title-main">Prairie Evaporite Formation</span> Geologic formation of Givetian age

The Prairie Evaporite Formation, also known as the Prairie Formation, is a geologic formation of Middle Devonian (Givetian) age that consists primarily of halite and other evaporite minerals. It is present beneath the plains of northern and eastern Alberta, southern Saskatchewan and southwestern Manitoba in Canada, and it extends into northwestern North Dakota and northeastern Montana in the United States.

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 Geology.com: Halite
  3. 1 2 "Halite" (PDF). Handbook of Mineralogy. Archived (PDF) from the original on June 28, 2010. Retrieved 16 April 2018.
  4. ↑ "Halite". Mindat.org. Archived from the original on 2011-08-05.
  5. ↑ "Halite". Webmineral. Archived from the original on 2004-11-24.
  6. ↑ Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). CRC Press. ISBN   978-1439855119.
  7. ↑ "halite". Merriam-Webster.com Dictionary . Merriam-Webster.
  8. ↑ "halite". Dictionary.com Unabridged (Online). n.d.
  9. ↑ "Halite". Random House Unabridged Dictionary . 1997. Archived from the original on 2015-10-02.
  10. ↑ Bonewitz, Ronald Louis (2012). Rocks and Minerals. DK Publishing. p. 110. ISBN   978-0-7566-9042-7.
  11. ↑ Sonnenfeld, Peter (January 1995). "The color of rock salt—A review". Sedimentary Geology. 94 (3–4): 267–276. Bibcode:1995SedG...94..267S. doi:10.1016/0037-0738(94)00093-A.
  12. ↑ "halite | mineral". Britannica. Retrieved 2022-04-22.
  13. ↑ "What is a Salt Dome? How do they form?". geology.com. Retrieved 2022-04-22.
  14. ↑ "HALITE (Sodium Chloride)". Galleries.com. Archived from the original on 2015-12-16. Retrieved 2015-12-16.
  15. ↑ Wales, University Of New South (2003). Beneath the Surface: A Natural History of Australian Caves. UNSW Press. ISBN   978-0-86840-595-7.
  16. ↑ "Where is the World's Largest Underground Salt Mine". 14 November 2018. Archived from the original on 2020-07-08. Retrieved 2019-04-10.
  17. ↑ Bitterman, Mark (2010). Salted: A Manifesto on the World's Most Essential Mineral, With Recipes. Ten Speed Press. pp. 267–270. ISBN   978-1-58008-262-4.
  18. ↑ Pre-wetting With Salt Brine. Center for Transportation Research and Education. 1996. ISBN   978-0965231008. Archived from the original on 2020-09-13. Retrieved 2019-04-10.
  19. ↑ Kurlansky, Mark (2003). Salt: A World History . Thorndike Press. ISBN   9780786243891.
  20. ↑ "Bible: Judges 9:45". Bible Hub. Archived from the original on October 30, 2018. Retrieved November 26, 2019.
  21. ↑ "Less Lethal Loadout: Rock Salt Shotgun Shells". 15 September 2020.
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