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{{Short description|Sedimentary carbonate rock that contains a high percentage of the mineral dolomite}}
[[File:7092 pieskovna Dolinka pri Hradisti pod Vratnom dolomit.JPG|thumb|upright=1.2|Triassic dolomitic rocks from [[Slovakia]]]]
[[File:Canadian Horseshoe Falls with city of Niagara Falls, Ontario in background.jpg|thumb|Erosion of dolomite over weaker shale created the [[Niagara Escarpment]]]]
[[File:Sthenarocalymene celebra - Arthropoda, Trilobita, Polymerida, Calymenidae - Silurian - Ohio, USA.jpg|thumb|[[Trilobite]] fossil preserved as an internal cast in [[Silurian]] dolomite from southwestern Ohio, USA]]
[[File:Cirque de Mourèze, Hérault 32.jpg|thumb|right|Erosion of dolomitic rocks in [[Mourèze]], Hérault, France]]
'''Dolomite''' (also known as '''dolomite rock''', '''dolostone''' or '''dolomitic rock''') is a [[sedimentary rock|sedimentary]] [[carbonate rock]] that contains a high percentage of the [[mineral]] [[Dolomite (mineral)|dolomite]], CaMg(CO3)2. It occurs widely, often in association with [[limestone]] and [[evaporite]]s, though it is less abundant than limestone and rare in [[Cenozoic]] rock beds (beds less than about 66 million years in age). The first geologist to distinguish dolomite rock from limestone was [[Belsazar Hacquet]] in 1778.<ref name="Kranjc">{{cite journal |title=Balthasar Hacquet (1739/40-1815), the Pioneer of Karst Geomorphologists |first=Andrej |last=Kranjc |journal=Acta Carsologica |volume=35 |issue=2 |year=2006 |issn=0583-6050 |publisher=Institute for the Karst Research, Scientific Research Centre, Slovenian Academy of Sciences and Arts |doi=10.3986/ac.v35i2-3.544 |doi-access=free }}</ref>

Most dolomite was formed as a magnesium replacement of limestone or of [[Lime (mineral)|lime]] mud before [[lithification]].<ref>{{cite book | last1=Zenger|first1= D. H.|last2=Mazzullo|first2= S. J.| title=Dolomitization| publisher=Hutchinson Ross| year=1982 | isbn=0-87933-416-9}}</ref> The geological process of conversion of [[calcite]] to dolomite is known as [[dolomitization]] and any intermediate product is known as '''dolomitic limestone'''.<ref>{{cite journal |last1=Chilingar |first1=George V. |last2=Bissell |first2=Harold J. |last3=Wolf |first3=Karl H. |title=Chapter 5 Diagenesis of Carbonate Rocks |journal=Developments in Sedimentology |date=1967 |volume=8 |page=314 |doi=10.1016/S0070-4571(08)70844-6|isbn=9780444533449 }}</ref><ref name="Geology">{{cite web|url=http://geology.com/rocks/dolomite.shtml|title=Dolomite. A sedimentary rock known as dolostone or dolomite rock|publisher=Geology.com|access-date=20 June 2014}}</ref> The "dolomite problem" refers to the vast worldwide depositions of dolomite in the past geologic record in contrast to the limited amounts of dolomite formed in modern times.<ref>{{Cite web|last=Fowles|first=Julian|date=25 October 1991|title=Dolomite: the mineral that shouldn't exist - Scientists have never been able to make dolomite in the way the mineral forms naturally. Theories have come and gone, but the mystery of its origins remains|url=https://www.newscientist.com/article/mg13217925-000/|access-date=2021-05-31|website=New Scientist|language=en-US}}</ref><ref>{{Cite journal|last1=Arvidson|first1=Rolf S.|last2=Mackenzie|first2=Fred T.|date=1999-04-01|title=The dolomite problem; control of precipitation kinetics by temperature and saturation state|journal=American Journal of Science|language=en|volume=299|issue=4|pages=257–288|doi=10.2475/ajs.299.4.257|bibcode=1999AmJS..299..257A|s2cid=49341088 |issn=0002-9599|doi-access=free}}</ref> Recent research has revealed sulfate-reducing bacteria living in anoxic conditions precipitate dolomite which indicates that some past dolomite deposits may be due to microbial activity.<ref name=VasconcelosEtal>{{Cite journal|last1=Vasconcelos|first1=Crisogono|last2=McKenzie|first2=Judith A.|author-link2=Judith Ann McKenzie (biogeochemist)|last3=Bernasconi|first3=Stefano|last4=Grujic|first4=Djordje|last5=Tiens|first5=Albert J.|date=1995|title=Microbial mediation as a possible mechanism for natural dolomite formation at low temperatures|journal=Nature|language=en|volume=377|issue=6546|pages=220–222|doi=10.1038/377220a0|bibcode=1995Natur.377..220V|s2cid=4371495|issn=1476-4687}}</ref><ref name=PetrashEtal>{{cite journal |last1=Petrash |first1=Daniel A. |last2=Bialik |first2=Or M. |last3=Bontognali |first3=Tomaso R.R. |last4=Vasconcelos |first4=Crisógono |last5=Roberts |first5=Jennifer A. |last6=McKenzie |first6=Judith A. |last7=Konhauser |first7=Kurt O. |title=Microbially catalyzed dolomite formation: From near-surface to burial |journal=Earth-Science Reviews |date=August 2017 |volume=171 |pages=558–582 |doi=10.1016/j.earscirev.2017.06.015|bibcode=2017ESRv..171..558P }}</ref>

Dolomite is resistant to [[erosion]] and can either contain [[Bed (geology)|bedded layers]] or be unbedded. It is less soluble than limestone in weakly [[acidic]] [[groundwater]], but it can still develop solution features ([[karst]]) over time. Dolomite rock can act as an oil and natural gas reservoir.

==Name==
Dolomite takes its name from the 18th-century French [[Mineralogy|mineralogist]] [[Déodat Gratet de Dolomieu]] (1750–1801), who was one of the first to describe the mineral.<ref>{{cite journal |last1=Mckenzie |first1=Judith A. |last2=Vasconcelos |first2=Crisogono |title=Dolomite Mountains and the origin of the dolomite rock of which they mainly consist: historical developments and new perspectives |journal=Sedimentology |date=January 2009 |volume=56 |issue=1 |pages=205–219 |doi=10.1111/j.1365-3091.2008.01027.x|bibcode=2009Sedim..56..205M |s2cid=128666364 }}</ref><ref>Saussure le fils, M. de (1792): "Analyse de la dolomite". ''Journal de Physique'', vol. 40, pp. 161–173.</ref>

The term ''dolomite'' refers to both the calcium-magnesium carbonate mineral and to sedimentary rock formed predominantly of this mineral. The term ''dolostone'' was introduced in 1948 to avoid confusion between the two. However, the usage of the term ''dolostone'' is controversial, because the name ''dolomite'' was first applied to the rock during the late 18th century and thus has technical precedence. The use of the term ''dolostone'' was not recommended by the ''Glossary of Geology'' published by the [[American Geological Institute]].<ref name="Glossary2005">{{cite book | title=Glossary of Geology | publisher=American Geological Institute | editor-last1=Neuendorf | editor-first1=K.K.E. | editor-last2=Mehl | editor-first2=J.P. Jr. | editor-last3=Jackson | editor-first3=J.A. | year=2005 | location=Alexandria, Virginia | page=189 | isbn=978-0922152896| edition=5th }}</ref>

In old [[USGS]] publications, dolomite was referred to as ''magnesian [[limestone]]'', a term now reserved for [[magnesium]]-deficient dolomites or magnesium-rich limestones.

==Description==
Dolomite rock is defined as [[sedimentary rock|sedimentary]] [[carbonate rock]] composed of more than 50% mineral [[Dolomite (mineral)|dolomite]]. Dolomite is characterized by its nearly ideal 1:1 [[stoichiometric ratio]] of magnesium to calcium. It is distinct from high-magnesium limestone in that the magnesium and calcium form ordered layers within the individual dolomite mineral grains, rather than being arranged at random, as they are in high-magnesium calcite grains.<ref>{{cite book |last1=Boggs |first1=Sam |title=Principles of sedimentology and stratigraphy |date=2006 |publisher=Pearson Prentice Hall |location=Upper Saddle River, N.J. |isbn=0131547283 |edition=4th |pages=160–161}}</ref> In natural dolomite, magnesium is typically between 44 and 50 percent of total magnesium plus calcium, indicating some substitution of calcium into the magnesium layers. A small amount of [[ferrous iron]] typically substitutes for magnesium, particularly in more ancient dolomites.<ref>{{cite book |last1=Blatt |first1=Harvey |last2=Middleton |first2=Gerard |last3=Murray |first3=Raymond |title=Origin of sedimentary rocks |date=1980 |publisher=Prentice-Hall |location=Englewood Cliffs, N.J. |isbn=0136427103 |edition=2d |pages=510–511}}</ref> Carbonate rock tends to be either almost all calcite or almost all dolomite, with intermediate compositions being quite uncommon.{{sfn|Blatt|Tracy|1996|p=318}}

Dolomite outcrops are recognized in the [[Field work|field]] by their softness (mineral dolomite has a Mohs hardness of 4 or less, well below common silicate minerals) and because dolomite bubbles feebly when a drop of dilute [[hydrochloric acid]] is dropped on it. This distinguishes dolomite from limestone, which is also soft but reacts vigorously with dilute hydrochloric acid. Dolomite usually weathers to a characteristic dull yellow-brown color due to the presence of ferrous iron. This is released and oxidized as the dolomite weathers.{{sfn|Blatt|Tracy|1996|p=295}} Dolomite is usually granular in appearance, with a [[Texture (geology)|texture]] resembling grains of [[sugar]].{{sfn|Boggs|2006|pp=167-168}}

Under the microscope, [[thin section]]s of dolomite usually show individual grains that are well-shaped [[Rhombohedron|rhombs]], with considerable pore space. As a result, subsurface dolomite is generally more porous than subsurface limestone and makes up 80% of carbonate rock [[petroleum reservoir]]s.{{sfn|Blatt|Middleton|Murray|1980|pp=529-530}} This texture contrasts with limestone, which is usually a mixture of grains, micrite (very fine-grained carbonate mud) and sparry cement. The optical properties of calcite and mineral dolomite are difficult to distinguish, but calcite almost never crystallizes as regular rhombs, and calcite is stained by [[Alizarin Red S]] while dolomite grains are not.{{sfn|Blatt|Tracy|1996|p=319}} Dolomite rock consisting of well-formed grains with planar surfaces is described as ''planar'' or ''idiotopic'' dolomite, while dolomite consisting of poorly-formed grains with irregular surfaces is described as ''nonplanar'' or ''xenotopic'' dolomite.{{sfn|Boggs|2006|pp=167-168}} The latter likely forms by recrystallization of existing dolomite at elevated temperature (over {{convert|50 to 100|C||sp=us}}).{{sfn|Blatt|Tracy|1996|p=319}}

The texture of dolomite often shows that it is secondary, formed by replacement of calcium by magnesium in limestone. The preservation of the original limestone texture can range from almost perfectly preserved to completely destroyed.{{sfn|Boggs|2006|p=168}} Under a microscope, dolomite rhombs are sometimes seen to replace [[oolite]]s or skeletal particles of the original limestone.{{sfn|Blatt|Middleton|Murray|1980|pp=512-513}} There is sometimes selective replacement of fossils, with the fossil remaining mostly calcite and the surrounding matrix composed of dolomite grains. Sometimes dolomite rhombs are seen cut across the fossil outline. However, some dolomite shows no textural indications that it was formed by replacement of limestone.{{sfn|Blatt|Tracy|1996|p=319}}

== Occurrence and origin ==
{{See also|Dolomitization}}
Dolomite is widespread in its occurrences, though not as common as limestone.{{sfn|Boggs|2006|p=169}} It is typically found in association with limestone or [[evaporite]] beds and is often [[interbedded]] with limestone.{{sfn|Boggs|2006|p=182}} There is no consistent trend in its abundance with age, but most dolomite appears to have formed at high stands of sea level. Little dolomite is found in [[Cenozoic]] beds (beds less than 65 million years old), which has been a time of generally low sea levels.{{sfn|Blatt|Tracy|1996|pp=317-318}} Times of high sea level also tend to be times of a [[greenhouse Earth]], and it is possible that greenhouse conditions are the trigger for dolomite formation.{{sfn|Boggs|2006|pp=187-188}}

Many dolomites show clear textural indications that they are secondary dolomites, formed by replacement of limestone. However, although much research has gone into understanding this process of ''dolomitization'', the process remains poorly understood. There are also fine-grained dolomites showing no textural indications that they formed by replacement, and it is uncertain whether they formed by replacement of limestone that left no textural traces or are true primary dolomites. This ''dolomite problem'' was first recognized over two centuries ago but is still not fully resolved.{{sfn|Boggs|2006|p=182}}

The dolomitization reaction

:{{chem2|2CaCO3 + Mg(2+) -> CaMg(CO3)2 + Ca(2+)}}

is thermodynamically favorable, with a [[Gibbs free energy]] of about -2.2 kcal/mol. In theory, ordinary [[seawater]] contains sufficient dissolved magnesium to cause dolomitization. However, because of the very slow rate of diffusion of ions in solid mineral grains at ordinary temperatures, the process can occur only by simultaneous dissolution of calcite and crystallization of dolomite. This in turn requires that large volumes of magnesium-bearing fluids are flushed through the pore space in the dolomitizing limestone.{{sfn|Blatt|Middleton|Murray|1980|pp=518-519}} Several processes have been proposed for dolomitization.

The hypersaline model (also known as the evaporative reflux model{{sfn|Blatt|Tracy|1996|p=321}}) is based on the observation that dolomite is very commonly found in association with limestone and [[evaporite]]s, with the limestone often interbedded with the dolomite. According to this model, dolomitization takes place in a closed basin where seawater is subject to high rates of evaporation. This results in precipitation of [[gypsum]] and [[aragonite]], raising the magnesium to calcium ratio of the remaining brine. The brine is also dense, so it sinks into the pore space of any underlying limestone (''seepage refluxion''), flushing out the existing pore fluid and causing dolomitization. The [[Permian Basin (North America)|Permian Basin]] of North America has been put forward as an example of an environment in which this process took place.{{sfn|Blatt|Tracy|1996|p=321}} A variant of this model has been proposed for [[sabkha]] environments in which brine is sucked up into the dolomitizing limestone by evaporation of capillary fluids, a process called ''evaporative pumping''.{{sfn|Blatt|Tracy|1996|p=321}}

Another model is the mixing-zone or Dorag model, in which [[meteoric water]] mixes with seawater already present in the pore space, increasing the chemical activity of magnesium relative to calcium and causing dolomitization. The formation of [[Pleistocene]] dolomite reefs in [[Jamaica]] has been attributed to this process. However, this model has been heavily criticized,{{sfn|Boggs|2006|pp=185-186}} with one 2004 review paper describing it bluntly as "a myth".<ref name="machel-2004">{{cite journal |last1=Machel |first1=Hans G. |title=Concepts and models of dolomitization: a critical reappraisal |journal=Geological Society, London, Special Publications |date=2004 |volume=235 |issue=1 |pages=7–63 |doi=10.1144/GSL.SP.2004.235.01.02|bibcode=2004GSLSP.235....7M |s2cid=131159219 }}</ref> A 2021 paper argued that the mixing zone serves as domain of intense microbial activity which promotes dolomitization.<ref>{{cite journal |last1=Petrash |first1=Daniel A. |last2=Bialik |first2=Or M. |last3=Staudigel |first3=Philip T. |last4=Konhauser |first4=Kurt O. |last5=Budd |first5=David A. |title=Biogeochemical reappraisal of the freshwater–seawater mixing‐zone diagenetic model |journal=Sedimentology |date=August 2021 |volume=68 |issue=5 |pages=1797–1830 |doi=10.1111/sed.12849|s2cid=234012426 }}</ref>

A third model postulates that normal seawater is the dolomitizing fluid, and the necessary large volumes are flushed through the dolomitizing limestone through tidal pumping. Dolomite formation at [[Sugarloaf Key]] may be an example of this process. A similar process might occur during rises in sea level, as large volumes of water move through limestone platform rock.{{sfn|Boggs|2006|pp=186-187}}

Regardless of the mechanism of dolomitization, the tendency of carbonate rock to be either almost all calcite or almost all dolomite suggests that, once the process is started, it completes rapidly.{{sfn|Blatt|Middleton|Murray|1980|pp=517-518}} The process likely occurs at shallow depths of burial, under {{convert|100|m||sp=us}}, where there is an inexhaustible supply of magnesium-rich seawater and the original limestone is more likely to be porous. On the other hand, dolomitization can proceed rapidly at the greater temperatures characterizing deeper burial, if a mechanism exists to flush magnesium-bearing fluids through the beds.{{sfn|Blatt|Tracy|1996|pp=322-323}}

Mineral dolomite has a 12% to 13% smaller volume than calcite per alkali cation. Thus dolomitization likely increases porosity and contributes to the sugary texture of dolomite.{{sfn|Blatt|Middleton|Murray|1980|pp=529-530}}

=== The dolomite problem and primary dolomite ===
Dolomite is supersaturated in normal seawater by a factor of greater than ten, but dolomite is not seen to precipitate in the oceans. Likewise, geologists have not been successful at precipitating dolomite from seawater at normal temperatures and pressures in laboratory experiments. This is likely due to a very high [[activation energy]] for [[nucleating]] crystals of dolomite.{{sfn|Blatt|Tracy|1996|p=323}}

The magnesium ion is a relatively small ion, and it acquires a tightly bound [[hydration shell]] when dissolved in water. In other words, the magnesium ion is surrounded by a clump of water molecules that are strongly attracted to its positive charge. Calcium is a larger ion and this reduces the strength of binding of its hydration shell, so it is much easier for a calcium ion than a magnesium ion to shed its hydration shell and bind to a growing crystal. It is also more difficult to nucleate a seed crystal of ordered dolomite than disordered high-magnesium calcite. As a result, attempts to precipitate dolomite from seawater precipitate high-magnesium calcite instead. This substance, which has an excess of calcium over magnesium and lacks calcium-magnesium ordering, is sometimes called '' protodolomite''.{{sfn|Blatt|Tracy|1996|p=323}} Raising the temperature makes it easier for magnesium to shed its hydration shell, and dolomite can be precipitated from seawater at temperatures in excess of {{convert|60|C||sp=us}}.{{sfn|Boggs|2006|pp=182-183}} Protodolomite also rapidly converts to dolomite at temperatures of {{convert|250|C||sp=us}} or higher.{{sfn|Blatt|Middleton|Murray|1980|pp=510-511}} The high temperatures necessary for the formation of dolomite helps explain the rarity of Cenozoic dolomites, since Cenozoic seawater temperatures seldom exceeded 40 °C.<ref>{{cite journal |last1=Ryb |first1=Uri |last2=Eiler |first2=John M. |date=11 June 2018 |title=Oxygen isotope composition of the Phanerozoic ocean and a possible solution to the dolomite problem |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=115 |issue=26 |pages=6602–6607 |doi=10.1073/pnas.1719681115 |pmid=29891710 |pmc=6042145 |doi-access=free }}</ref>

It is possible that microorganisms are capable of precipitating primary dolomite.<ref name=PetrashEtal/> This was first demonstrated in samples collected at [[Lagoa Vermelha]], [[Brazil]]<ref name=VasconcelosEtal/> in association with [[sulfate-reducing bacteria]] (''[[Desulfovibrio]]''), leading to the hypothesis that [[sulfate ion]] inhibits dolomite nucleation. Later laboratory experiments suggest bacteria can precipitate dolomite independently of the sulfate concentration.<ref name=SanchezRomanEtal>{{cite journal |last1=Sánchez-Román |first1=Mónica |last2=McKenzie |first2=Judith A. |last3=de Luca Rebello Wagener |first3=Angela |last4=Rivadeneyra |first4=Maria A. |last5=Vasconcelos |first5=Crisógono |title=Presence of sulfate does not inhibit low-temperature dolomite precipitation |journal=[[Earth and Planetary Science Letters]] |date=July 2009 |volume=285 |issue=1–2 |pages=131–139 |doi=10.1016/j.epsl.2009.06.003|bibcode=2009E&PSL.285..131S }}</ref> With time other pathways of interaction between microbial activity and dolomite formation have been added to the discord regarding their role in modulation and generation of [[polysaccharides]],<ref>{{cite journal |last1=Zhang |first1=F. |last2=Xu |first2=H. |last3=Konishi |first3=H. |last4=Shelobolina |first4=E. S. |last5=Roden |first5=E. E. |title=Polysaccharide-catalyzed nucleation and growth of disordered dolomite: A potential precursor of sedimentary dolomite |journal=[[American Mineralogist]] |date=1 April 2012 |volume=97 |issue=4 |pages=556–567 |doi=10.2138/am.2012.3979|bibcode=2012AmMin..97..556Z |s2cid=101903513 }}</ref> [[manganese]]<ref>{{cite journal |last1=Daye |first1=Mirna |last2=Higgins |first2=John |last3=Bosak |first3=Tanja |title=Formation of ordered dolomite in anaerobic photosynthetic biofilms |journal=[[Geology (journal)|Geology]] |date=1 June 2019 |volume=47 |issue=6 |pages=509–512 |doi=10.1130/G45821.1|bibcode=2019Geo....47..509D |hdl=1721.1/126802 |s2cid=146426700 |hdl-access=free }}</ref><ref>{{cite journal |last1=Li |first1=Weiqiang |last2=Bialik |first2=Or M. |last3=Wang |first3=Xiaomin |last4=Yang |first4=Tao |last5=Hu |first5=Zhongya |last6=Huang |first6=Qingyu |last7=Zhao |first7=Shugao |last8=Waldmann |first8=Nicolas D. |title=Effects of early diagenesis on Mg isotopes in dolomite: The roles of Mn(IV)-reduction and recrystallization |journal=[[Geochimica et Cosmochimica Acta]] |date=April 2019 |volume=250 |pages=1–17 |doi=10.1016/j.gca.2019.01.029|bibcode=2019GeCoA.250....1L |s2cid=134838668 }}</ref> and [[zinc]]<ref>{{cite journal |last1=Vandeginste |first1=Veerle |last2=Snell |first2=Oliver |last3=Hall |first3=Matthew R. |last4=Steer |first4=Elisabeth |last5=Vandeginste |first5=Arne |title=Acceleration of dolomitization by zinc in saline waters |journal=[[Nature Communications]] |date=December 2019 |volume=10 |issue=1 |pages=1851 |doi=10.1038/s41467-019-09870-y|pmid=31015437 |pmc=6478858 |bibcode=2019NatCo..10.1851V }}</ref> within the porewater. Meanwhile, a contrary view held by other researchers is that microorganisms precipitate only high-magnesium calcite but leave open the question of whether this can lead to precipitation of dolomite.<ref>{{cite journal |last1=Gregg |first1=Jay M. |last2=Bish |first2=David L. |last3=Kaczmarek |first3=Stephen E. |last4=Machel |first4=Hans G. |title=Mineralogy, nucleation and growth of dolomite in the laboratory and sedimentary environment: A review |journal=Sedimentology |date=October 2015 |volume=62 |issue=6 |pages=1749–1769 |doi=10.1111/sed.12202|s2cid=130135125 }}</ref>

=== Dedolomitization ===
Dolomitization can sometimes be reversed, and a dolomite bed converted back to limestone. This is indicated by a texture of [[pseudomorph]]s of mineral dolomite that have been replaced with calcite. Dedolomitized limestone is typically associated with gypsum or oxidized [[pyrite]], and dedolomitization is thought to occur at very shallow depths through infiltration of surface water with a very high ratio of calcium to magnesium. {{sfn|Blatt|Middleton|Murray|1980|pp=531-532}}

== Uses ==
[[File:Saaremaa dolomiit 1994 (04).jpg|thumb|Cutting dolomite in 1994. [[Saaremaa]], [[Estonia]].]]
Dolomite is used for many of the same purposes as limestone, including as [[construction aggregate]]; in agriculture to neutralize soil acidity and supply calcium and magnesium; as a source of [[carbon dioxide]]; as [[dimension stone]]; as a [[Filler (materials)|filler]] in fertilizers and other products; as a flux in [[metallurgy]]; and in [[glass manufacturing]]. It cannot substitute for limestone in chemical processes that require a high-calcium limestone, such as manufacture of [[sodium carbonate]]. Dolomite is used for production of magnesium chemicals, such as [[Epsom salt]], and is used as a magnesium supplement.<ref>{{cite journal |last1=Lamar |first1=J.E. |title=Uses of limestone and dolomite |journal=Illinois State Geological Survey Circular |date=1961 |volume=321 |url=https://www.ideals.illinois.edu/bitstream/handle/2142/42725/usesoflimestoned321lama.pdf?sequence=2 |access-date=15 September 2021}}</ref> It is also used in the manufacture of [[refractory materials]].<ref>{{cite book |last1=Clancy |first1=T.A. |last2=Benson |first2=D.J. |year=2009 |chapter=Refractory Dolomite Raw Materials |title=Raw Materials for Refractories Conference |volume=38 |page=119 |publisher=John Wiley & Sons |isbn=9780470320488 |chapter-url=https://books.google.com/books?id=XqVGQTIQh0gC&dq=uses+of+dolomite&pg=PA119 |access-date=14 September 2021}}</ref>

==Caves in dolomite rock==
As with limestone [[cave]]s, natural caves and solution tubes typically form in dolomite rock as a result of the [[Dissolution (chemistry)|dissolution]] by weak carbonic acid.<ref name=Hill&Forti1997>Hill, C A and Forti, P, (1997). Cave Minerals of the World, Second editions. [Huntsville, Alabama: National Speleological Society Inc.] pp 14, 142, 143, 144 & 150, {{ISBN|1-879961-07-5}}</ref><ref name=White&Culver2005>White W.B and Culver D.C., (2005) Chapter "Caves, Definitions of", Encyclopedia of Caves, edited by Culver D.C and White W.B., {{ISBN|0-12-406061-7}}</ref> Caves can also, less commonly, form through dissolution of rock by [[sulfuric acid]].<ref>{{cite journal| last1 = Polyak | first1 = Victor J.| last2 = Provencio| first2 = Paula | date = 2000| title = By-product materials related to H2S-H2SO4-influenced speleogenesis of Carlsbad, Lechuguilla, and other caves of the Guadalupe Mountains, New Mexico| journal = Journal of Cave and Karst Studies| volume = 63| issue = 1| pages = 23–32| url = https://www.researchgate.net/publication/242359913
| access-date = 4 April 2020}}</ref> [[Calcium carbonate]] [[speleothem]]s (secondary deposits) in the forms of [[stalactite]]s, [[stalagmite]]s, [[flowstone]] etc., can also form in caves within dolomite rock. “Dolomite is a common rock type, but a relatively uncommon mineral in speleothems”.<ref name=Hill&Forti1997 />
Both the 'Union Internationale de Spéléologie' (UIS) and the American 'National Speleological Society' (NSS), extensively use in their publications, the terms "dolomite" or "dolomite rock" when referring to the natural bedrock containing a high percentage of CaMg(CO3)2 in which natural caves or solution tubes have formed.<ref name=Hill&Forti1997 /><ref name=Culver&White>Encyclopedia of Caves, (2005). Edited by Culver D.C and White W.B., {{ISBN|0-12-406061-7}}</ref>

===Dolomite speleothems===
Both calcium and magnesium go into solution when dolomite rock is dissolved. The [[speleothem]] precipitation sequence is: [[calcite]], Mg-calcite, [[aragonite]], [[huntite]] and [[hydromagnesite]].<ref name=Hill&Forti1997 /><ref name=Culver&White /> Hence, the most common speleothem (secondary deposit) in caves within dolomite rock [[karst]], is calcium carbonate in the most stable [[Polymorphism (materials science)|polymorph]] form of calcite. Speleothem types known to have a dolomite constituent include: coatings, crusts, [[moonmilk]], [[flowstone]], coralloids, powder, spar and rafts.<ref name=Hill&Forti1997 /> Although there are reports of dolomite speleothems known to exist in a number of caves around the world, they are usually in relatively small quantities and form in very fine-grained deposits.<ref name=Hill&Forti1997 /><ref name=Culver&White />

==See also==
* [[Diagenesis]]

==References==
{{Reflist}}

==Further reading==
*{{cite book | last1=Blatt|first1=Harvey |first2=Robert J. |last2=Tracy| title=Petrology; Igneous, Sedimentary, and Metamorphic |edition= 2nd |publisher=W. H. Freeman| year=1996 | isbn=0-7167-2438-3}}
*{{cite book | last1=Tucker|first1= M. E. |author-link = Maurice Tucker|first2=Wright|last2= V. P.| title=Carbonate Sedimentology| publisher=Blackwell Scientific Publications| year=1990 | isbn=0-632-01472-5}}

==External links==
* [http://www.wisegeek.org/what-is-dolomitic-limestone.htm What is Dolomitic Limestone?]
{{Rock type}}
{{Commons category|Dolostone}}
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[[Category:Dolomite (rock)| ]]
[[Category:Dolomite group]]

Dolomite (rock) - Revision history

Ajay Kumar: Created a new article