# Evaporite

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An **evaporite** (/ᵻˈvæpəˌraɪt/) is a water-[soluble](/source/Solubility) [sedimentary](/source/Sedimentation) [mineral](/source/Mineral) [deposit](/source/Deposition_(geology)) caused by the concentration and [crystallization](/source/Crystallization) ([chemical precipitation](/source/Precipitation_(chemistry))) that results when enough of the water [solvent](/source/Solvent) [evaporates](/source/Evaporation) from an [aqueous solution](/source/Aqueous_solution).[1] 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](/source/Sedimentary_rock) and are formed by chemical [sediments](/source/Sediment).

## Formation

Although all water bodies on the surface and in [aquifers](/source/Aquifers) contain dissolved [salts](/source/Salts), the water must evaporate into the [atmosphere](/source/Atmosphere) for the minerals to precipitate. For this to happen, the water body must enter a restricted environment where water input into this environment remains below the net rate of evaporation. This is usually an [arid](/source/Arid) environment with a small [drainage basin](/source/Drainage_basin) fed by a limited input of water. When evaporation occurs, the remaining water is enriched in [salts](/source/Salt_(chemistry)), and they precipitate after the water becomes saturated.

## Depositional environments

### Marine

Marine evaporites tend to have thicker deposits and are usually the focus of more extensive research.[2] When scientists evaporate [ocean water](/source/Seawater) in a laboratory, the minerals are deposited in a defined order that was first demonstrated by Usiglio in 1884.[2] The first phase of precipitation begins when about 50% of the original water depth remains. At this point, minor [carbonates](/source/Carbonate) begin to form.[2] The next phase in the sequence comes when the experiment is left with about 20% of its original level. At this point, the mineral [gypsum](/source/Gypsum) begins to form, which is then followed by [halite](/source/Halite) at 10%,[2] excluding carbonate minerals that tend not to be evaporites. The most common marine evaporites are [calcite](/source/Calcite), gypsum and [anhydrite](/source/Anhydrite), halite, [sylvite](/source/Sylvite), [carnallite](/source/Carnallite), [langbeinite](/source/Langbeinite), [polyhalite](/source/Polyhalite), and [kainite](/source/Kainite). [Kieserite](/source/Kieserite) (MgSO4) may also be included, which often will make up less than four percent of the overall content.[2] However, there are approximately 80 different minerals that have been reported found in evaporite deposits,[3][4] though only about a dozen are common enough to be considered important rock formers.[2]

### Non-marine

Non-marine evaporites are usually composed of minerals that are not common in marine environments because in general the water from which non-marine evaporite precipitates has proportions of chemical elements different from those found in the marine environments.[2] Common minerals that are found in these deposits include [blödite](/source/Bl%C3%B6dite), [borax](/source/Borax), [epsomite](/source/Epsomite), [gaylussite](/source/Gaylussite), [glauberite](/source/Glauberite), [mirabilite](/source/Mirabilite), [thenardite](/source/Thenardite) and [trona](/source/Trona). Non-marine deposits may also contain halite, gypsum, and anhydrite, and may in some cases even be dominated by these minerals, although they did not come from ocean deposits. This, however, does not make non-marine deposits any less important; these deposits often help to paint a picture into past Earth climates. Some particular deposits even show important tectonic and climatic changes. These deposits also may contain important minerals that help in today's economy.[5] Thick non-marine deposits that accumulate tend to form where evaporation rates will exceed the inflow rate, and where there is sufficient soluble supplies. The inflow also has to occur in a closed basin, or one with restricted outflow, so that the sediment has time to pool and form in a lake or other standing body of water.[5] Primary examples of this are called "saline lake deposits".[5] Saline lakes includes things such as perennial lakes, which are lakes that are there year-round, playa lakes, which are lakes that appear only during certain seasons, or any other terms that are used to define places that hold standing bodies of water intermittently or year-round. Examples of modern non-marine depositional environments include the [Great Salt Lake](/source/Great_Salt_Lake) in Utah and the [Dead Sea](/source/Dead_Sea), which lies between Jordan and Israel.

Evaporite [depositional environments](/source/Sedimentary_depositional_environment) that meet the above conditions include:

- [Graben](/source/Graben) areas and [half-grabens](/source/Half-graben) within continental [rift](/source/Rift_(geology)) environments fed by limited riverine drainage, usually in subtropical or tropical environments - Example environments at the present that match this is the [Denakil Depression](/source/Denakil_Depression), Ethiopia; [Death Valley](/source/Death_Valley), [California](/source/California)
- Graben environments in oceanic rift environments fed by limited oceanic input, leading to eventual isolation and evaporation - Examples include the Red Sea, and the [Dead Sea](/source/Dead_Sea) in Jordan and Israel
- Internal drainage basins in arid to semi-arid temperate to tropical environments fed by ephemeral drainage - Example environments at the present include the [Simpson Desert](/source/Simpson_Desert), [Western Australia](/source/Western_Australia), the [Great Salt Lake](/source/Great_Salt_Lake) in [Utah](/source/Utah)
- Non-basin areas fed exclusively by groundwater seepage from artesian waters - Example environments include the seep-mounds of the Victoria Desert, fed by the [Great Artesian Basin](/source/Great_Artesian_Basin), Australia
- Restricted coastal plains in regressive sea environments - Examples include the [sabkha](/source/Sabkha) deposits of Iran, Saudi Arabia, and the Red Sea; the [Garabogazköl](/source/Garabogazk%C3%B6l) of the [Caspian Sea](/source/Caspian_Sea)
- Drainage basins feeding into extremely arid environments - Examples include the Chilean deserts, certain parts of the [Sahara](/source/Sahara), and the [Namib](/source/Namib)

The most significant known evaporite depositions happened during the [Messinian salinity crisis](/source/Messinian_salinity_crisis) in the basin of the [Mediterranean](/source/Mediterranean).

## Evaporitic formations

Evaporite formations need not be composed entirely of [halite](/source/Halite) salt. In fact, most evaporite formations do not contain more than a few percent of evaporite minerals, the remainder being composed of the more typical [detrital](/source/Detrital) [clastic](/source/Clastic) rocks and [carbonates](/source/Carbonate). Examples of evaporite formations include occurrences of evaporite sulfur in Eastern Europe and West Asia.[6]

For a formation to be recognised as evaporitic it may simply require recognition of halite [pseudomorphs](/source/Pseudomorph), sequences composed of some proportion of evaporite minerals, and recognition of mud crack textures or other [textures](/source/Rock_microstructure).

## Economic importance

Evaporites are important economically because of their mineralogy, their physical properties in-situ, and their behaviour within the subsurface.

Evaporite minerals, especially nitrate minerals, are economically important in Peru and Chile. Nitrate minerals are often mined for use in the production on [fertilizer](/source/Fertilizer) and [explosives](/source/Explosive).

Thick halite deposits are expected to become an important location for the disposal of [nuclear waste](/source/Nuclear_waste) because of their geologic stability, predictable engineering and physical behaviour, and imperviousness to groundwater.

Halite formations are famous for their ability to form [diapirs](/source/Diapir), which produce ideal locations for trapping [petroleum](/source/Petroleum) deposits.

Halite deposits are often mined for use as [salt](/source/Salt).

## Major groups of evaporite minerals

This is a chart that shows minerals that form the marine evaporite rocks. They are usually the most common minerals that appear in this kind of deposit.

Mineral class Mineral name Chemical composition Chlorides Halite NaCl Sylvite KCl Carnallite KMgCl3 * 6 H2O Kainite KMg(SO4)Cl * 3 H2O Sulfates Anhydrite CaSO4 Gypsum CaSO4 * 2 H2O Kieserite MgSO4 * H2O Langbeinite K2Mg2(SO4)3 Polyhalite K2Ca2Mg(SO4)6 * H2O Carbonates Dolomite CaMg(CO3)2 Calcite CaCO3 Magnesite MgCO3

- [Halides](/source/Halide_mineral): [halite](/source/Halite), [sylvite](/source/Sylvite) (KCl), and [fluorite](/source/Fluorite)
- [Sulfates](/source/Sulfate_mineral): such as [gypsum](/source/Gypsum), [barite](/source/Barite), and [anhydrite](/source/Anhydrite)
- [Nitrates](/source/Nitrate_mineral): [nitratine](/source/Nitratine) (soda niter) and [niter](/source/Niter)
- [Borates](/source/Borate_mineral): typically found in arid-salt-lake deposits plentiful in the [southwestern US](/source/Southwestern_US). A common borate is [borax](/source/Borax), which has been used in [soaps](/source/Soap) as a [surfactant](/source/Surfactant).
- [Carbonates](/source/Carbonate_mineral): such as [trona](/source/Trona), formed in inland brine lakes. - Some evaporite minerals, such as [hanksite](/source/Hanksite), are from multiple groups.

Evaporite minerals start to [precipitate](/source/Precipitation_(chemistry)) when their concentration in water reaches such a level that they can no longer exist as [solutes](/source/Solutes).

The minerals precipitate out of solution in the reverse order of their solubilities, such that the order of precipitation from sea water is:

1. [Calcite](/source/Calcite) (CaCO3) and [dolomite](/source/Dolomite_(mineral)) (CaMg(CO3)2)
1. Gypsum (CaSO4 * 2 [[H2O]]) and anhydrite (CaSO4).
1. Halite (i.e. common salt, NaCl)
1. [Potassium](/source/Potassium) and [magnesium](/source/Magnesium) salts

The abundance of rocks formed by seawater precipitation is in the same order as the precipitation given above. Thus, [limestone](/source/Limestone) (dolomite) is more common than [gypsum](/source/Gypsum), which is more common than halite, which is more common than potassium and magnesium salts.

Evaporites can also be easily [recrystallized](/source/Recrystallization_(chemistry)) in laboratories in order to investigate the conditions and characteristics of their formation.

## Possible evaporites on Titan

Recent evidence from [satellite observations](/source/Remote_sensing)[7] and laboratory experiments[8] suggest evaporites are likely present on the surface of [Titan](/source/Titan_(moon)), Saturn's largest moon. Instead of water oceans, Titan hosts [lakes and seas of liquid hydrocarbons](/source/Lakes_of_Titan) (mainly methane) with many soluble hydrocarbons, such as [acetylene](/source/Acetylene),[9] that can evaporate out of solution. Evaporite deposits cover large regions of Titan's surface, mainly along the coastlines of lakes or in isolated [basins](/source/Basin_(geology)) ([Lacunae](/source/List_of_geological_features_on_Titan#Lacunae)) that are equivalent to [salt pans](/source/Salt_pan_(geology)) on Earth.[10]

## See also

- [List of minerals](/source/List_of_minerals)
- [List of rock types](/source/List_of_rock_types)
- [Salt dome](/source/Salt_dome)

## References

1. Jackson, Julia A. (1997). *Glossary of Geology*. 4th ed. [Alexandria, Virginia](/source/Alexandria,_Virginia): [American Geological Institute](/source/American_Geosciences_Institute)

1. Boggs, Sam (2006). *Principles of sedimentology and stratigraphy*. 4th ed. Upper Saddle River, N.J.: Pearson Prentice Hall. ISBN 0131547283.

1. Stewart, F.H. (1963). "Marine evaporites". *U.S. Geological Society Professional Paper*. **440-Y**: 21. [Bibcode:1963usgs.rept...21S](https://ui.adsabs.harvard.edu/abs/1963usgs.rept...21S). [doi:10.3133/pp440Y](https://doi.org/10.3133/pp440Y)

1. Warren, John (1999). *Evaporites : their evolution and economics*. Oxford: Blackwell Science. ISBN 978-0632053018.

1. *Evaporites, petroleum and mineral resources*. Amsterdam: Elsevier. 1991. ISBN 978-0444555762.

1. C.Michael Hogan. 2011. [*Sulfur*. Encyclopedia of Earth, eds. A.Jorgensen and C.J.Cleveland, National Council for Science and the environment, Washington DC](http://www.eoearth.org/article/Sulfur?topic=49557) [Archived](https://web.archive.org/web/20121028080550/http://www.eoearth.org/article/Sulfur?topic=49557) October 28, 2012 at the Wayback Machine

1. Barnes, Jason W.; Bow, Jacob; Schwartz, Jacob; Brown, Robert H.; Soderblom, Jason M.; Hayes, Alexander G.; Vixie, Graham; Le Mouélic, Stéphane; Rodriguez, Sebastien; Sotin, Christophe; Jaumann, Ralf (2011-11-01). ["Organic sedimentary deposits in Titan's dry lakebeds: Probable evaporite"](http://www.sciencedirect.com/science/article/pii/S0019103511003393). *Icarus*. **216** (1): 136–140. [Bibcode:2011Icar..216..136B](https://ui.adsabs.harvard.edu/abs/2011Icar..216..136B). [doi:10.1016/j.icarus.2011.08.022](https://doi.org/10.1016/j.icarus.2011.08.022). [ISSN 0019-1035](https://www.worldcat.org/issn/0019-1035)

1. Czaplinski, Ellen C.; Gilbertson, Woodrow A.; Farnsworth, Kendra K.; Chevrier, Vincent F. (2019-10-17). "Experimental Study of Ethylene Evaporites under Titan Conditions". *ACS Earth and Space Chemistry*. **3** (10): 2353–2362. [arXiv:2002.04978](https://arxiv.org/abs/2002.04978). [Bibcode:2019ESC.....3.2353C](https://ui.adsabs.harvard.edu/abs/2019ESC.....3.2353C). [doi:10.1021/acsearthspacechem.9b00204](https://doi.org/10.1021/acsearthspacechem.9b00204). [S2CID 202875048](https://api.semanticscholar.org/CorpusID:202875048)

1. Singh, S.; Combe, J. -Ph.; Cordier, D.; Wagner, A.; Chevrier, V. F.; McMahon, Z. (2017-07-01). ["Experimental determination of acetylene and ethylene solubility in liquid methane and ethane: Implications to Titan's surface"](http://www.sciencedirect.com/science/article/pii/S0016703717301448). *Geochimica et Cosmochimica Acta*. **208**: 86–101. [Bibcode:2017GeCoA.208...86S](https://ui.adsabs.harvard.edu/abs/2017GeCoA.208...86S). [doi:10.1016/j.gca.2017.03.007](https://doi.org/10.1016/j.gca.2017.03.007). [ISSN 0016-7037](https://www.worldcat.org/issn/0016-7037)

1. MacKenzie, S. M. & Barnes, Jason W. (2016-04-05). "Compositional Similarities and Distinctions Between Titan's Evaporitic Terrains". *The Astrophysical Journal*. **821** (1): 17. [arXiv:1601.03364](https://arxiv.org/abs/1601.03364). [Bibcode:2016ApJ...821...17M](https://ui.adsabs.harvard.edu/abs/2016ApJ...821...17M). [doi:10.3847/0004-637x/821/1/17](https://doi.org/10.3847/0004-637x/821/1/17). [ISSN 1538-4357](https://www.worldcat.org/issn/1538-4357)

## Other reading

- [California State University evaporites page](https://web.archive.org/web/20060912123341/http://seis.natsci.csulb.edu/bperry/Sedimentary%20Rocks%20Tour/evaporites.htm)
- Gore, Rick (December 1982). "The Mediterranean: Sea of Man's Fate". *National Geographic*
- Guéguen, Yves & Palciauskas, Vector (1994). *Introduction to the physics of rocks*. Princeton, N.J.: Princeton University Press. ISBN 9780691034522.

- Hardie, Lawrence, 1984, "Evaporites: marine or nonmarine?: *American Journal of Science*, v. 284, pp. 193–240. [doi:10.2475/ajs.284.3.193](https://doi.org/10.2475/ajs.284.3.193)
- Hardie, L.A., and Eugster, H.P., 1971, "The depositional environment of marine evaporites: a case for shallow, clastic accumulation": *Sedimentology*, v. 16, p. 187–220.
- Benison, K.C., and Goldstein, R.H., 2002, "Recognizing acid lakes and groundwaters in the rock record": *Sedimentary Geology*, v. 151, pp. 177–185.

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Adapted from the Wikipedia article [Evaporite](https://en.wikipedia.org/wiki/Evaporite) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Evaporite?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.