Malachite: Difference between revisions - Wikipedia

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{{Other uses}}

{{Distinguish|Malachite green}}

{{Lead too short|date=May 2022}}

{{Infobox mineral

| name = Malachite

| category = [[Carbonate mineral]]

| boxbgcolor =#3fce68▼

| boxwidth =

| image = Malachite, Zaire.jpg▼

▲| boxbgcolor =#3fce68

| alt = ▼

▲| image = Malachite, Zaire.jpg

| caption = Malachite from the [[Democratic Republic of the Congo]]▼

▲| alt =

| formula = Cu₂CO₃(OH)₂▼

▲| caption = Malachite from the [[Democratic Republic of the Congo]]

| IMAsymbol = Mlc<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|url=https://www.cambridge.org/core/journals/mineralogical-magazine/article/imacnmnc-approved-mineral-symbols/62311F45ED37831D78603C6E6B25EE0A|journal=Mineralogical Magazine|volume=85|issue=3 |pages=291–320|doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 |doi-access=free}}</ref>▼

▲| formula = Cu₂CO₃(OH)₂

| molweight = 221.1 g/mol

▲| IMAsymbol = Mlc<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|url=https://www.cambridge.org/core/journals/mineralogical-magazine/article/imacnmnc-approved-mineral-symbols/62311F45ED37831D78603C6E6B25EE0A|journal=Mineralogical Magazine|volume=85|issue=3 |pages=291–320|doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 }}</ref>

| molweight strunz = 2215.1 g/molBA.10

| system = [[Monoclinic]]▼

| strunz = 5.BA.10

| class = Prismatic (2/m) <br /><small>(same [[H-M symbol]])</small>▼

▲| system = [[Monoclinic]]

| symmetry = ''P2''₁/a▼

▲| class = Prismatic (2/m) <br /><small>(same [[H-M symbol]])</small>

| color = Bright green, dark green, blackish green, with crystals deeper shades of green, even very dark to nearly black commonly banded in masses; green to yellowish green in transmitted light ▼

▲| symmetry = ''P2''₁/a

| habit = Massive, botryoidal, stalactitic, crystals are acicular to tabular prismatic▼

▲| color = Bright green, dark green, blackish green, with crystals deeper shades of green, even very dark to nearly black commonly banded in masses; green to yellowish green in transmitted light

| twinning = Common as contact or penetration twins on {{mset|100}} and {{mset|201}}. Polysynthetic twinning also present.

▲| habit = Massive, botryoidal, stalactitic, crystals are acicular to tabular prismatic

| twinning cleavage = Common as contact or penetration twinsPerfect on {{mset|100{{overline|2}}01}} andfair on {{mset|201010}}. Polysynthetic twinning also present.

| fracture = Subconchoidal to uneven▼

| cleavage = Perfect on {{mset|{{overline|2}}01}} fair on {{mset|010}}

| mohs = 3.5–4▼

▲| fracture = Subconchoidal to uneven

| luster = Adamantine to vitreous; silky if fibrous; dull to earthy if massive▼

▲| mohs = 3.5–4

| refractive = n_α = 1.655 n_β = 1.875 n_γ = 1.909▼

▲| luster = Adamantine to vitreous; silky if fibrous; dull to earthy if massive

▲| refractive = n_α = 1.655 n_β = 1.875 n_γ = 1.909

| opticalprop = Biaxial (–)

| birefringence = δ = 0.254

| pleochroism =

| streak = light green

| gravity = 3.6–4

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity = Translucent to opaque

| other =

| references =<ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Malachite Mineralienatlas]</ref><ref name=Handbook>{{cite book|editor1=Anthony, John W. |editor2=Bideaux, Richard A. |editor3=Bladh, Kenneth W. |editor4=Nichols, Monte C. |title= Handbook of Mineralogy|publisher= Mineralogical Society of America|place= Chantilly, Virginia|chapter-url=http://rruff.geo.arizona.edu/doclib/hom/malachite.pdf|chapter=Malachite|isbn=0962209740 |volume=V (Borates, Carbonates, Sulfates)|year=2003}}</ref><ref>[http://webmineral.com/data/Malachite.shtml Malachite]. Webmineral</ref><ref name=Mindat>[http://mindat.org/min-2550.html Malachite]. Mindat</ref>

}}

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==Etymology and history==

[[File:Great Orme Copper Mine - geograph.org.uk - 819.jpg|thumb|left|The entrance to the [[Neolithic era]] malachite mine complex on the Great Orme, Wales]]

The stone's name derives (via {{lang-la|molochītis}}, {{lang-frm|melochite}}, and [[Middle English]] ''melochites'') from [[Greek language|Greek]] Μολοχίτης λίθος ''molochites lithos'', "mallow-green stone", from μολόχη ''molochē'', variant of μαλάχη ''malāchē'', "mallow".<ref>[http://dictionary.reference.com/browse/Malachite Malachite], Dictionary.com</ref> The mineral was given this name due to its resemblance to the leaves of the [[Malva|mallow plant]].<ref>{{OEtymD|malachite}}</ref> Copper (Cu²⁺) gives malachite its green color.<ref>{{Cite web |title=Minerals Colored by Metal Ions |url=http://minerals.gps.caltech.edu/color_causes/Metal_Ion/index.html |access-date=2023-03-01 |website=minerals.gps.caltech.edu}}</ref>

Malachite was mined from deposits near the Isthmus of Suez and the Sinai as early as 4000 BCE.<ref>{{cite journal |last1= Susarla |first1=S.M |date= 2016 |title= The colourful history of malachite green: from ancient Egypt to modern surgery |url= https://www.ijoms.com/article/S0901-5027(16)30250-8/fulltext |journal= International Journal of Oral and Maxillofacial Surgery|volume=46 |issue=3 |pages=401–403 |doi=10.1016/j.ijom.2016.09.022 |pmid=27771151 }}</ref>

It was extensively mined at the [[Great Orme Mines]] in Britain 3,800 years ago, using stone and bone tools. Archaeological evidence indicates that mining activity ended {{circa|600 BCE}}, with up to 1,760 tonnes of copper being produced from the mined malachite.<ref name="Histuk">{{Cite web |url=http://www.historic-uk.com/HistoryUK/HistoryofWales/the-great-orme-mines/ |title=The Great Orme Mines |year=2014 |editor-last=Johnson |editor-first=Ben |access-date=2017-06-06}}</ref><ref>{{Cite web |url=http://www.bbc.com/earth/story/20160420-the-ancient-copper-mines-dug-by-bronze-age-children |title=The Ancient Copper Mines Dug By Bronze Age Children |last=Ruggeri |first=Amanda |date=21 April 2016 |publisher=BBC |access-date=2017-06-06}}</ref>

Archaeological evidence indicates that the mineral has been mined and smelted to obtain copper at [[Timna Valley]] in [[Israel]] for more than 3,000 years.<ref>Parr, Peter J. (1974). "Review of 'Timma: Valley of the Biblical Copper Mines' by [[Beno Rothenberg]] ''Bulletin of the School of Oriental and African Studies'', University of London, Vol. 37, No. 1, pp. 223–224</ref> Since then, malachite has been used as both an ornamental stone and as a gemstone.

The use of [[azurite]] and malachite as copper ore indicators led indirectly to the name of the element [[nickel]] in the English language. [[Nickeline]], a principal ore of nickel that is also known as niccolite, weathers at the surface into a green mineral ([[annabergite]]) that resembles malachite. This resemblance resulted in occasional attempts to [[smelting|smelt]] nickeline in the belief that it was copper ore, but such attempts always ended in failure due to high smelting temperatures needed to [[redox|reduce]] nickel. In Germany this deceptive mineral came to be known as [[List of chemical element name etymologies#N|''kupfernickel'']], literally "copper [[demon]]." The [[Sweden|Swedish]] [[Alchemy#The decline of European alchemy|alchemist]] Baron [[Axel Fredrik Cronstedt]] (who had been trained by [[Georg Brandt]], the discoverer of the nickel-like metal [[cobalt]]) realized that there was probably a new metal hiding within the kupfernickel ore, and in 1751 he succeeded in smelting kupfernickel to produce a previously unknown (except in certain [[iron meteorite|meteorites]]) silvery white, iron-like metal. Logically, Cronstedt named his new metal after the ''nickel'' part of ''kupfernickel''.

==Occurrence==

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Malachite often results from the [[Supergene (geology)|supergene]] weathering and oxidation of [[Hypogene|primary]] [[Sulfide mineral|sulfidic]] [[List of copper ores|copper]] [[ore]]s, and is often found with [[azurite]] (Cu₃(CO₃)₂(OH)₂), [[goethite]], and [[calcite]]. Except for its vibrant green color, the properties of malachite are similar to those of azurite and aggregates of the two minerals occur frequently. Malachite is more common than [[azurite]] and is typically associated with copper deposits around [[limestone]]s, the source of the carbonate.

Large quantities of malachite have been mined in the [[Urals]], [[Russia]]. Ural malachite is not being mined at present,<ref>[http://gazeta.aif.ru/_/online/aif/1334/46_02 Куда делись символы России?] {{Webarchive|url=https://web.archive.org/web/20131202231359/http://gazeta.aif.ru/_/online/aif/1334/46_02 |date=2013-12-02 }} [[Argumenty i Fakty]] (24 May 2006)</ref> but G.N Vertushkova reports the possible discovery of new deposits of malachite in the Urals.<ref>Somin, L. M. [http://oldrushistory.ru/library/Tayny-sedogo-Urala/46 Тайны седого Урала. Малахит]. oldrushistory.ru</ref> It is found worldwide including in the [[Democratic Republic of the Congo]]; [[Gabon]]; [[Zambia]]; [[Tsumeb]], [[Namibia]]; [[Mexico]]; [[Broken Hill, New South Wales]]; [[Burra, South Australia]]; [[Lyon]], [[France]]; [[Timna Valley]], [[Israel]]; and the [[Southwestern United States]], most notably in [[Arizona]].<ref>[http://www.mindat.org/show.php?id=2550&ld=1#themap Mindat map with over 8500 locations]. mindat.org</ref>

[[Human impact on the environment|Anthropogenic]] malachite was historically believed to be the primary component of the [[patina]] which forms on [[copper]] and copper alloy structures exposed to open-air [[weathering]]; however, atmospheric sources of sulfate and chloride (such as air pollution or sea winds) typically favour the formation of [[brochantite]] or [[atacamite]].<ref>{{cite journal|title=Basic copper carbonate and green patina|author=W. H. J. Vernon|journal=J. Chem. Soc.|year=1934|doi=10.1039/JR9340001853}}</ref> Malachite can also be produced synthetically, in which case it is referred to as [[basic copper carbonate]] or green verditer.

==Structure==

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File:Malachite 100.png|View along ''a'' axis of malachite crystal structure

File:Malachite 010.png|View along ''b'' axis of malachite crystal structure

</gallery>

<gallery>

File:Malachite-unit-cell-3D-bs-17.png|[[Unit cell]] of malachite

File:Malachite-xtalformula-Cu1unit-and-coordination-fade-25-from-xtal-3D-bs-N1717-M2525.png|[[CoordinationFormula environmentunit]] ofand copperits 1[[coordination environment]]

File:Malachite-xtal-Cu2Cu1-coordination-3D-bs-N17-M25.png|Coordination environment of copper 2#1

File:Malachite-xtal-Cu2-coordination-3D-bs-N17-M25.png|Coordination environment of copper #2

File:Malachite-xtal-carbonate-coordination-3D-bs-N17-M25.png|Coordination environment of [[carbonate]]

File:Malachite-xtal-hydroxide-O4-coordination-3D-bs-N17-M25.png|Coordination environment of [[hydroxide]] #1

File:Malachite-xtal-hydroxide-O5-coordination-3D-bs-N17-M25.png|Coordination environment of hydroxide #2

</gallery>

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Malachite was used as a mineral pigment in green paints from antiquity until {{circa}} 1800.<ref>Gettens, R.J. and Fitzhugh, E. W. (1993) "Malachite and Green Verditer", pp. 183–202 in ''Artists’ Pigments. A Handbook of Their History and Characteristics'', Vol. 2: A. Roy (Ed.) Oxford University Press. {{ISBN|0894682601}}</ref> The pigment is moderately [[Lightfastness|lightfast]], sensitive to [[acid]]s, and varying in color. This natural form of green pigment has been replaced by its synthetic form, [[Basic_copper_carbonate|verditer]], among other synthetic greens.

Malachite is also used for decorative purposes, such as in wands and the [[Malachite Room of the Winter Palace|Malachite Room]] in the [[Hermitage Museum]],<ref>{{Cite journal|last=Budrina|first=Ludmila|title=Малахитовые залы Петербурга, России, Европы... / Malachite salon of St.-Petersburg, Russia, Europe...|url=https://www.academia.edu/7717944|journal=// Блистательный Петербург. Роль архитекторов ХIХ века в создании неповторимого облика города. Материалы научно-практической конференции. Кафедра. Сб. науч. Ст. – СПб.: Государственный музей-памятник «Исаакиевский собор», 2011. – С. 23-49.|date=January 2011|language=en}}</ref> which features a huge malachite vase, and the Malachite Room in [[Castillo de Chapultepec]] in [[Mexico City]].<ref>{{Cite journal|last=Budrina|first=Ludmila|title=La produzione in malachite dei Demidov: sulle trace degli oggetti alla prima esposizione universale / I Demidoff fra Russia e Italia. Gusto e prestigio di une famiglia in Europa dal XVIII al XX secolo. – P. 151-176, 9 tav.|url=https://www.academia.edu/7803720|journal=// I Demidoff Fra Russia e Italia. Gusto e Prestigio di Une Famiglia in Europa Dal XVIII al XX Secolo. A Cura di Lucia Tonini. Cultura e Memoria, Vol. 50. – Firenze: Leo S. Olschki, 2013.|date=January 2013|language=en}}</ref> Another example is the Demidov Vase, part of the former [[Demidov Collection|Demidov family collection]], and now in the [[Metropolitan Museum of Art]].<ref>[https://www.metmuseum.org/art/collection/search/199500 Monumental vase lapidary work: early 19th century; pedestal and mounts: 1819] Metropolitan Museum of Art. Retrieved 25 April 2021.</ref> "The [[Tazza (cup)|Tazza]]", a large malachite vase, one of the largest pieces of malachite in North America and a gift from [[Nicholas II of Russia|Tsar Nicholas II]], stands as the focal point in the centre of the room of [[Linda Hall Library]]. In the time of [[Nicholas I of Russia|Tsar Nicolas I]] decorative pieces with malachite were among the most popular diplomatic gifts.<ref>{{Cite book|last=Будрина|first=Людмила|title=Малахитовая дипломатия|publisher=Кабинетный ученый|year=2020|isbn=978-5-6044025-1-1|location=Екатеринбург|pages=208}}</ref> It was used in China as far back as the [[Eastern Zhou]] period.<ref>{{cite journal |last1=Langhals |first1=Heinz |last2=Bathelt |first2=Daniela |title=The Restoration of the Largest Archaelogical Discovery—a Chemical Problem: Conservation of the Polychromy of the Chinese Terracotta Army in Lintong |journal=Angewandte Chemie International Edition |date=1 December 2003 |volume=42 |issue=46 |pages=5676–5681 |doi=10.1002/anie.200301633|pmid=14661198 }}</ref> The base of [[FIFA World Cup Trophy]] has two layers of malachite.

===Symbolism and superstitions===

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In [[ancient Egypt]] the colour green (wadj) was associated with death and the power of resurrection as well as new life and fertility. Ancient Egyptians believed that the [[afterlife]] contained an eternal paradise, referred to as the "Field of Malachite", which resembled their lives but with no pain or suffering.<ref>{{Cite web|url=http://www.ancientegyptonline.co.uk/colourgreen.html|title=Meaning of green in ancient Egypt|last=Hill|first=J|date=2010|website=Ancient Egypt Online|access-date=2016-11-28}}</ref>

=== Ore uses ===

[[File:Natural_copper_nugget.jpg|thumb|Copper nugget example]]

Simple methods of [[copper ore]] extraction from malachite involved thermodynamic processes such as [[smelting]].<ref name=":0Johnson-2004">{{Cite journal|last1=Johnson|first1=Cris E.|last2=Yee|first2=Gordon T.|last3=Eddleton|first3=Jeannine E.|date=2004-12-01|title=Copper Metal from Malachite circa 4000 B.C.E.|url=https://doi.org/10.1021/ed081p1777|journal=Journal of Chemical Education|volume=81|issue=12|pages=1777|doi=10.1021/ed081p1777|bibcode=2004JChEd..81.1777J|issn=0021-9584}}</ref> This reaction involves the addition of heat and a carbon, causing the carbonate to decompose leaving [[Copper(II) oxide|copper oxide]] and an additional carbon source such as coal converts the copper oxide into copper metal.<ref name=":0Johnson-2004" /><ref name=":1Day-2019">{{Citation|last1=Day|first1=Jo|title=Reconstructing a Bronze Age Kiln from Priniatikos Pyrgos, Crete|date=2019-09-30|url=http://dx.doi.org/10.2307/j.ctvpmw4g8.11|work=Experimental Archaeology: Making, Understanding, Story-telling|pages=63–72|publisher=Archaeopress Publishing Ltd|isbn=978-1-78969-320-1|access-date=2021-02-25|last2=Kobik|first2=Maggie|doi=10.2307/j.ctvpmw4g8.11|s2cid=210629355}}</ref>

The basic word equation for this reaction is:

Copper carbonate + heat → carbon dioxide + copper oxide (color changes from green to black).<ref name=":0Johnson-2004" /><ref name=":1Day-2019" />

Copper oxide + carbon → carbon dioxide + copper (color change from black to copper colored).<ref name=":0Johnson-2004" /><ref name=":1Day-2019" />

Malachite is a low grade copper ore, however, due to increase demand for metals, more economic processing such as [[Hydrometallurgy|hydrometallurgical]] methods (using aqueous solutions such as [[sulfuric acid]]) are being used as malachite is readily soluble in dilute acids.<ref>{{Cite journal|last1=Ata|first1=O. N.|last2=Yalap|first2=H.|date=2007-06-01|title=Optimization of Copper Leaching from Ore Containing Malachite|url=https://doi.org/10.1179/cmq.2007.46.2.107|journal=Canadian Metallurgical Quarterly|volume=46|issue=2|pages=107–114|doi=10.1179/cmq.2007.46.2.107|bibcode=2007CaMQ...46..107A |s2cid=98163205|issn=0008-4433}}</ref><ref>{{Cite web|title=Malachite|url=https://www.mindat.org/min-2550.html|access-date=2021-03-12|website=www.mindat.org}}</ref> [[Sulfuric acid]] is the most common leaching agent for copper oxide ores like malachite and eliminates the need for smelting processes.<ref name=":22Shabani-2012">{{Cite journal|last1=Shabani|first1=M. A.|last2=Irannajad|first2=M.|last3=Azadmehr|first3=A. R.|date=2012-09-01|title=Investigation on leaching of malachite by citric acid|url=https://doi.org/10.1007/s12613-012-0628-9|journal=International Journal of Minerals, Metallurgy, and Materials|language=en|volume=19|issue=9|pages=782–786|doi=10.1007/s12613-012-0628-9|bibcode=2012IJMMM..19..782S|s2cid=96128268|issn=1869-103X}}</ref>

The chemical equation for sulfuric acid leaching of copper ore from malachite is as follows:<ref name=":22Shabani-2012"/>

{{NumBlk|:

|{{overset|malachite|{{chem2|Cu2(OH)2CO3}}}} + {{overset|sulfuric acid|{{chem2|2H2SO4}}}} → {{overset|copper sulfate|{{chem2|2CuSO4}}}} + {{overset|carbon dioxide|{{chem2|CO2}}}} + {{overset|water|{{chem2|3H2O}}}}

|{{EquationRef|Reaction 1}}}}

== Health and environmental concerns ==

Mining for malachite for ornamental or copper ore purposes involves [[open-pit mining]] or [[underground mining]] depending on the grade of the ore deposits.<ref>{{Cite web|title=Malachite|url=http://www.mine-engineer.com/mining/mineral/malachite.htm#:~:text=The%20distinctive%20bright-green%20hydrous,of%20other%20copper%20ore%20minerals.&text=Ores%20are%20removed%20either%20by%20open-pit%20or%20by%20underground%20mining.|access-date=2021-03-25|website=www.mine-engineer.com}}</ref> Open-pit and underground mining practices can cause [[environmental degradation]] through [[Habitat destruction|habitat]] and [[biodiversity loss]].<ref>{{Cite journal|last1=Monjezi|first1=M.|last2=Shahriar|first2=K.|last3=Dehghani|first3=H.|last4=Samimi Namin|first4=F.|date=2009-07-01|title=Environmental impact assessment of open pit mining in Iran|url=https://doi.org/10.1007/s00254-008-1509-4|journal=Environmental Geology|language=en|volume=58|issue=1|pages=205–216|doi=10.1007/s00254-008-1509-4|bibcode=2009EnGeo..58..205M|s2cid=128616763|issn=1432-0495}}</ref><ref name=":3Salomons-1995">{{Cite journal|last=Salomons|first=W.|date=1995-01-01|title=Environmental impact of metals derived from mining activities: Processes, predictions, prevention|url=https://dx.doi.org/10.1016%2F0375-6742%2894%2900039-E|journal=Journal of Geochemical Exploration|series=Heavy Metal Aspects of Mining Pollution and Its Remediation|language=en|volume=52|issue=1|pages=5–23|doi=10.1016/0375-6742(94)00039-E|bibcode=1995JCExp..52....5S |issn=0375-6742}}</ref> [[Acid mine drainage]] can contaminate water and food sources to negatively impact human health if improperly managed or if leaks from [[Tailings|tailing ponds]] occur.<ref name=":3Salomons-1995" /><ref>{{Cite web|title=Environmental Impact of Sulfuric Acid Leaching|url=http://www.savethesantacruzaquifer.info/Sulfuric%20Acid%20Impact.htm|access-date=2021-03-25|website=www.savethesantacruzaquifer.info}}</ref> The risk of health and environmental impacts of both traditional metallurgy and newer methods of hydrometallurgy are both significant,<ref name=":3Salomons-1995" /> however, water conservation and waste management practices for hydrometallurgy processes for ore extraction, such as for malachite, are stricter and relatively more sustainable.<ref>{{Cite journal|last=Conard|first=Bruce R.|date=1992-06-01|title=The role of hydrometallurgy in achieving sustainable development|url=https://dx.doi.org/10.1016%2F0304-386X%2892%2990074-A|journal=Hydrometallurgy|series=Hydrometallurgy, Theory and Practice Proceedings of the Ernest Peters International Symposium. Part B|language=en|volume=30|issue=1|pages=1–28|doi=10.1016/0304-386X(92)90074-A|bibcode=1992HydMe..30....1C |issn=0304-386X}}</ref> New research is also being conducted on better alternatives to methods such as sulfuric acid leaching which has high environmental impacts, even under hydrometallurgy regulation standards and innovation.<ref name=":22Shabani-2012"/>

==Gallery==

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File:Malachite, image taken under a stereoscopic microscope.jpg|Malachite, image taken under a stereoscopic microscope

File:Calendar (part of a set) MET DP-13486-011.jpg |British calendar, 1851, gilt bronze and malachite, height: 20.3&nbsp;cm, [[Metropolitan Museum of Art]] (New York City)

File:Malachite at Kaleideum Children's Museum.jpg|Malachite at [[Kaleideum]] Children's Museum

File:Elephant in malachite Length 11 cm arp.jpg|Elephant carved from malachite. Length 11&nbsp;cm.

File:Malachite-71023.jpg|A polished slice of malachite through three intergrown stalactites with bulls-eye banding

</gallery>