Editing Calcite (section)

== Use and applications ==
[[File:Tutankhamun's Alabaster Jar.jpg|thumb|upright|left|One of several calcite or alabaster perfume jars from the tomb of [[Tutankhamun]], d.&nbsp;1323 BC]]
Ancient Egyptians carved many items out of calcite, relating it to their goddess [[Bastet|Bast]], whose name contributed to the term [[alabaster]] because of the close association. Many other cultures have used the material for similar carved objects and applications.<ref>{{cite news |last1=Reed |first1=Kristina |title=Display Case |work=La Sierra Digs |issue=2 |publisher=La Sierra University |date=Spring 2017 |volume=5 |url=https://lasierra.edu/fileadmin/documents/cnea/newsletter/cnea-newsletter-spring-2017.pdf |access-date=6 February 2021}}</ref>

A transparent variety of calcite known as [[Iceland spar]] may have been used by [[Vikings]] for navigating on cloudy days. A very pure crystal of calcite can split a beam of sunlight into dual images, as the polarized light deviates slightly from the main beam. By observing the sky through the crystal and then rotating it so that the two images are of equal brightness, the rings of polarized light that surround the sun can be seen even under overcast skies. Identifying the sun's location would give seafarers a reference point for navigating on their lengthy sea voyages.<ref>{{cite journal |last1=Perkins |first1=Sid |title=Viking seafarers may have navigated with legendary crystals |journal=Science |date=3 April 2018 |doi=10.1126/science.aat7802 |doi-access=free}}</ref>

In World War II, high-grade optical calcite was used for gun sights, specifically in bomb sights and anti-aircraft weaponry.<ref>{{cite web|url=https://www.sandiegouniontribune.com/sdut-borregos-calcite-mine-trail-holds-desert-wonders-2010dec05-htmlstory.html|title=Borrego's calcite mine trail holds desert wonders|first1=Priscilla|last1=Lister|website=The San Diego Union-Tribune|date=December 5, 2010|access-date=January 8, 2021}}</ref> It was used as a polarizer (in [[Nicol prism]]s) before the invention of [[Polaroid (polarizer)|Polaroid]] plates and still finds use in optical instruments.{{sfn|Klein|Hurlbut|1993|p=408}} Also, experiments have been conducted to use calcite for a [[cloak of invisibility]].<ref>{{cite journal |last1=Chen |first1=Xianzhong |last2=Luo |first2=Yu |last3=Zhang |first3=Jingjing |last4=Jiang |first4=Kyle |last5=Pendry |first5=John B. |last6=Zhang |first6=Shuang |doi=10.1038/ncomms1176 |title=Macroscopic invisibility cloaking of visible light |pmid=21285954 |year=2011 |page=176 |volume=2 |journal=Nature Communications |issue=2 |pmc=3105339 |bibcode=2011NatCo...2..176C |arxiv=1012.2783}}</ref>

[[Microbiologically induced calcite precipitation|Microbiologically precipitated calcite]] has a wide range of applications, such as soil remediation, soil stabilization and concrete repair.<ref>{{cite journal |last1=Mujah |first1=D. |last2=Shahin |first2=M. A. |last3=Cheng |first3=L. |title=State-of-the-Art Review of Biocementation by Microbially Induced Calcite Precipitation (MICP) for Soil Stabilization. |journal=Geomicrobiology Journal |date=2017 |volume=34 |issue=6 |pages=524–537 |doi=10.1080/01490451.2016.1225866 |bibcode=2017GmbJ...34..524M |s2cid=88584080}}</ref><ref>{{cite journal |last1=Castro-Alonso |first1=M. J. |last2=Montañez-Hernandez |first2=L. E. |last3=Sanchez-Muñoz |first3=M. A. |last4=Macias Franco |first4=M. R. |last5=Narayanasamy |first5=R. |last6=Balagurusamy |first6=N. |title=Microbially induced calcium carbonate precipitation (MICP) and its potential in bioconcrete: microbiological and molecular concepts. |journal=Frontiers in Materials |date=2019 |volume=6 |page=126 |doi=10.3389/fmats.2019.00126 |bibcode=2019FrMat...6..126C |doi-access=free }}</ref> It also can be used for tailings management and is designed to promote sustainable development in the mining industry.<ref>{{cite journal |last1=Zúñiga-Barra |first1=H. |last2=Toledo-Alarcón |first2=J. |last3=Torres-Aravena |first3=Á. |last4=Jorquera |first4=L. |last5=Rivas |first5=M. |last6=Gutiérrez |first6=L. |last7=Jeison |first7=D. |title=Improving the sustainable management of mining tailings through microbially induced calcite precipitation: A review. |journal=Minerals Engineering |date=2022 |volume=189 |page=107855– |doi=10.1016/j.mineng.2022.107855 |s2cid=252986388}}</ref>

Calcite can help synthesize precipitated calcium carbonate (PCC) (mainly used in the paper industry) and increase [[carbonation]].<ref name=Jimoh>{{cite journal |last1=Jimoh |first1=O. A. |last2=Ariffin |first2=K. S. |last3=Hussin |first3=H. B. |last4=Temitope |first4=A. E. |title=Synthesis of precipitated calcium carbonate: a review. |journal=Carbonates and Evaporites |date=2018 |volume=33 |issue=2 |pages=331–346 |doi=10.1007/s13146-017-0341-x |s2cid=133034902}}</ref> Furthermore, due to its particular crystal habit, such as rhombohedron, hexagonal prism, etc., it promotes the production of PCC with specific shapes and particle sizes.<ref name=Jimoh />

Calcite, obtained from an 80&nbsp;kg sample of [[Carrara marble]],<ref name="IAEA603RefSheet">{{cite web |url=https://nucleus.iaea.org/rpst/ReferenceProducts/ReferenceMaterials/Stable_Isotopes/13C18and7Li/IAEA-603/RM603_Reference_Sheet_2016-08-16.pdf |title=Reference Sheet: Certified Reference Material: IAEA-603 (calcite) – Stable Isotope Reference Material for δ<sup>13</sup>C and δ<sup>18</sup>O |publisher=[[IAEA]] |author=Department of Nuclear Sciences and Applications, IAEA Environment Laboratories |date=16 July 2016 |access-date=28 February 2017 |page=2}}</ref> is used as the [[IAEA]]-603 isotopic standard in [[mass spectrometry]] for the calibration of [[δ18O|δ<sup>18</sup>O]] and [[δ13C|δ<sup>13</sup>C]].<ref>{{cite web|title=IAEA-603, Calcite |url=https://nucleus.iaea.org/rpst/ReferenceProducts/ReferenceMaterials/Stable_Isotopes/13C18and7Li/IAEA-603/index.htm |website=Reference Products for Environment and Trade |publisher=International Atomic Energy Agency |access-date=27 February 2017}}</ref>

Calcite can be formed naturally or synthesized. However, artificial calcite is the preferred material to be used as a scaffold in bone tissue engineering due to its controllable and repeatable properties.<ref>{{cite journal |last1=Chróścicka |first1=A. |last2=Jaegermann |first2=Z. |last3=Wychowański |first3=P. |last4=Ratajska |first4=A. |last5=Sadło |first5=J. |last6=Hoser |first6=G. |last7=Michałowski |first7=S. |last8=Lewandowska-Szumiel |first8=M. |title=Synthetic Calcite as a Scaffold for Osteoinductive Bone Substitutes. |journal=Annals of Biomedical Engineering |date=2016 |volume=44 |issue=7 |pages=2145–2157 |doi=10.1007/s10439-015-1520-3 |pmid=26666226 |pmc=4893069 |doi-access=free}}</ref>

Calcite can be used to alleviate water pollution caused by the excessive growth of [[cyanobacteria]]. Lakes and rivers can lead to cyanobacteria blooms due to [[eutrophication]], which pollutes water resources.<ref name=Han>{{cite journal |last1=Han |first1=M. |last2=Wang |first2=Y. |last3=Zhan |first3=Y. |last4=Lin |first4=J. |last5=Bai |first5=X. |last6=Zhang |first6=Z. |title=Efficiency and mechanism for the control of phosphorus release from sediment by the combined use of hydrous ferric oxide, calcite and zeolite as a geo-engineering tool. |journal=Chemical Engineering Journal |date=2022 |volume=428 |page=131360– |doi=10.1016/j.cej.2021.131360|bibcode=2022ChEnJ.42831360H }}</ref> Phosphorus (P) is the leading cause of excessive growth of cyanobacteria.<ref name=Han /> As an active capping material, calcite can help reduce P release from sediments into the water, thus inhibiting cyanobacteria overgrowth.<ref name=Han />