View source for Rhodochrosite

{{Short description|Mineral of manganese carbonate}}
{{Use British English|date=January 2023}}
{{Use dmy dates|date=January 2023}}
{{Infobox mineral
| name        = Rhodochrosite
| category    = [[Carbonate minerals]]
| image       = Rhodochrosite on Matrix - Peru.jpg
| caption     =
| formula     = MnCO<sub>3</sub>
| IMAsymbol   = Rds<ref>{{Cite journal|last=Warr|first=L.N.|year=2021|title=IMA–CNMNC approved mineral symbols|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>
| molweight   = 114.95 g/mol
| strunz      = 5.AB.05
| system      = [[Trigonal]]
| class       = Hexagonal scalenohedral ({{overline|3}}m) <br />[[H-M symbol]]: ({{overline|3}} 2/m)
| symmetry    = ''R''{{overline|3}}c
| unit cell   = a = 4.777, c = 15.67&nbsp;[Å]; Z&nbsp;=&nbsp;6
| color       = Pink, rose, rose-red, red, cherry-red, yellow, yellowish grey, grey, cinnamon-brown, white, may be banded; colourless to pale rose in transmitted light.
| habit       = Rhombohedral and scalenohedral crystals; also commonly bladed, columnar, stalactitic, botryoidal, granular or massive
| twinning    = On {10{{overline|1}}2} as contact and lamellar
| cleavage    = On {10{{overline|1}}1} perfect; parting on {10{{overline|1}}2}
| fracture    = Uneven, conchoidal
| tenacity    = Brittle
| mohs        = 3.5–4
| lustre      = [[Vitreous lustre|Vitreous]] to pearly
| polish      =
| refractive  = n<sub>ω</sub> = 1.814–1.816<br> n<sub>ε</sub> = 1.596–1.598
| opticalprop = Uniaxial (−)
| birefringence = δ = 0.218
| dispersion  =
| pleochroism = weak
| fluorescence= None
| absorption  =
| streak      = White
| gravity     = 3.7
| density     =
| melt        =
| fusibility  =
| diagnostic  =
| solubility  =
| diaphaneity = Transparent to translucent
| other       =
| references  =<ref name=HBM>{{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, VA, US|url=http://rruff.geo.arizona.edu/doclib/hom/rhodochrosite.pdf|chapter=Rhodochrosite|isbn=0962209740 |volume=V (Borates, Carbonates, Sulfates)|year=2003}}
</ref><ref name=Mindat>[http://www.mindat.org/min-3406.html Rhodochrosite]. Mindat.org</ref><ref name=Webmin>[http://webmineral.com/data/Rhodochrosite.shtml Rhodochrosite]. Webmineral</ref>
}}

'''Rhodochrosite''' is a [[manganese]] [[carbonate mineral]] with chemical composition [[Manganese(II) carbonate|MnCO<sub>3</sub>]]. In its pure form (rare), it is typically a rose-red colour,<ref>{{cite book |url=https://books.google.com/books?id=Rz0kukaagQsC&pg=PA150 |pages=150–152 |title=Rock-forming Minerals: Non-Silicates |volume=5B |author=Deer, William Alexander |publisher=Geological Society of London |year=1998|isbn=9781897799901 }}</ref> but it can also be shades of pink to pale brown. It [[Streak (mineralogy)|streaks]] white,<ref name="Cairncross">{{cite book |url=https://books.google.com/books?id=9w1bDwAAQBAJ&pg=PA180 |page=180 |title=Understanding Minerals & Crystals |author=Cairncross, Bruce |publisher=Penguin Random House South Africa |year=2015|isbn=9781775843344 }}</ref> and its [[Mohs hardness]] varies between 3.5 and 4.5. Its [[specific gravity]] is between 3.45 and 3.6.<ref>{{cite book |url=https://books.google.com/books?id=-XSAML4RhPsC&pg=PA3 |page=3 |title=Manganese: General Information |author=Ridgway, Robert Henderson |publisher=U.S. Department of the Interior, Bureau of Mines |year=1933}}</ref> The crystal system of rhodochrosite is [[trigonal system|trigonal]], with a structure and [[Cleavage (crystal)|cleavage]] in the carbonate [[rhombohedral system]]. The carbonate ions ({{Chem|CO|3|2-}}) are arranged in a triangular planar configuration, and the [[manganese]] ions (Mn<sup>2+</sup>) are surrounded by six oxygen ions in an octahedral arrangement. The MnO<sub>6</sub> octahedra and CO<sub>3</sub> triangles are linked together to form a three-dimensional structure. [[Crystal twinning]] is often present. It can be confused with the manganese silicate [[rhodonite]], but is distinctly softer.<ref>[https://www.mindat.org/min-3407.html Rhodonite]. Mindat.org</ref> Rhodochrosite is formed by the oxidation of manganese [[ore]], and is found in [[South Africa]], [[China]], and the [[Americas]].<ref name="Cairncross"/> It is one of the [[national symbols of Argentina]] and the state of [[Colorado]].

Rhodochrosite forms a complete [[solid solution]] series with iron carbonate ([[siderite]]). [[Calcium]] (as well as [[magnesium]] and [[zinc]], to a limited extent) frequently substitutes for manganese in the structure, leading to lighter shades of red and pink, depending on the degree of substitution. This is the reason for the rose color of rhodochrosite.

==Occurrence and discovery==
Rhodochrosite occurs as a hydrothermal vein mineral along with other manganese minerals in low temperature ore deposits as in the silver mines of Romania where it was first found. Banded rhodochrosite is mined in Capillitas, [[Argentina]].

It was first described in 1813 in reference to a sample from [[Cavnic]], [[Maramureș County|Maramureș]], present-day [[Romania]]. The name is derived from the combination of [[Greek (language)|Greek]] words ροδόν (rodon, meaning ''rose'') and χρωσις (chrosis, meaning ''coloring'').<ref name=HBM/>

==Use==
Rhodochrosite is mainly used as an ore of [[manganese]], which is a key component of low-cost stainless steel formulations, many [[tool steel]]s, and certain aluminium alloys.<ref>{{cite book|title=Nature's Building Blocks: An A-Z Guide to the Elements|last=Emsley|first=John|publisher=Oxford University Press|date=2001|location=Oxford, UK|isbn=978-0-19-850340-8|chapter=Manganese|page=251}}</ref> Quality banded specimens are often used for decorative stones and jewellery. Due to its softness and perfect [[Cleavage (crystal)|cleavage]] it is rarely found faceted in jewellery and is also sought after by many collectors.<ref>{{cite book | last=Matlins | first=Antoinette Leonard | title=Colored gemstones : the Antoinette Matlins buying guide : how to select, buy, care for & enjoy sapphires, emeralds, rubies, and other colored gems with confidence and knowledge | publisher=GemStone Press | publication-place=Woodstock, Vt. | date=2005 | isbn=978-0-943763-45-3 | oclc=60374175 | page=143}}</ref>

Manganese carbonate is extremely destructive to the [[Pan amalgamation|amalgamation]] process historically used in the concentration of [[silver ore]]s, and were often discarded on the mine dump.

==Culture==
{{stereo image
 |image   = Rhodochrosite3d.jpg
 |caption = Small Rhodochrosite specimen featured in a mineral kit, from Wuton mine, [[Guangxi]], China<!-- DO NOT LINK, see [[MOS:GEOLINK]] for further guidance -->.
 |width   = 500
 |height  = 200
}}

Rhodochrosite is Argentina's "national [[gemstone]]".<ref>{{cite web|url=http://www.ecolo.mrecic.gov.ar/content/piedra-nacional-la-rodocrosita|title=Piedra nacional: la Rodocrosita|publisher=Embassy of the Argentine Republic in the Colombian Republic|access-date=7 October 2013|language=es}}</ref><ref>{{cite news|url=http://www.pagina12.com.ar/diario/placer/16-12298-2002-11-09.html|title=La piedra argentina|author=Moreno, María|newspaper=[[Página/12]]|date=9 November 2002|access-date=7 October 2013|language=es}}</ref> [[Colorado]] officially named rhodochrosite as its state mineral in 2002.<ref>{{cite web |url=http://www.colorado.gov/dpa/doit/archives/history/symbemb.htm#Mineral |archive-url=https://web.archive.org/web/20030814083930/http://www.colorado.gov/dpa/doit/archives/history/symbemb.htm#Mineral |url-status=dead |archive-date=14 August 2003 |title=Colorado State Archives; Symbols & Emblems |access-date=2 February 2012}}</ref>

It is sometimes called "Rosa del Inca", "Inca Rose" or ''Rosinca''.<ref name="GemRocks">{{cite web|publisher= Central Michigan University|url=http://stoneplus.cst.cmich.edu/Rhodochrosite.htm|title=Rhodochrosite|author=Dietrich, R.&nbsp;V.|date=16 July 2005|access-date=15 August 2007}}</ref>

==Gallery==
<gallery widths="200" heights="200">
File:The Searchlight Rhodochrosite Crystal.jpg|"The Searchlight," a large red rhodochrosite from [[Sweet Home Mine]], Alma, Colorado<!-- DO NOT LINK, see [[MOS:GEOLINK]] for further guidance -->, U.S.
File:Fluorite-Quartz-Rhodochrosite-ed10a.jpg|Rhodochrosite with [[fluorite]], [[tetrahedrite]] and quartz.
File:Rhodochrosite Pink Form.jpg|Rhodochrosite from [[Silverton, Colorado]], U.S.
File:Alma King rhodochrosite.jpg|The ''Alma King'' is the largest known rhodochrosite crystal; it was found in the Sweet Home Mine near [[Alma, Colorado]] and donated to the [[Denver Museum of Nature and Science]].
File:Rodocrosita 2.jpg|Exhibit in [[La Plata Museum]], Argentina.
File:The Alma Rose.jpg|The ''Alma Rose'' specimen from the Sweet Home Mine. On display at the [[Rice Northwest Museum of Rocks and Minerals]] in [[Hillsboro, Oregon]], U.S.
File:Rhodochrosite Argentina.jpg|Rhodochrosite from [[Argentina]]
</gallery>

==See also==
* [[List of minerals]]
* [[Manganoan calcite]]

==References==
{{Reflist|2}}
* Hurlbut, Cornelius S.; Klein, Cornelis, 1985, ''Manual of Mineralogy'', 20th ed., {{ISBN|0-471-80580-7}}.

== External links ==
{{Wikisource1911Enc|Rhodochrosite}}

* {{Commons category-inline}}

{{Manganese minerals}}
{{National emblems of Argentina}}

[[Category:Carbonate minerals]]
[[Category:Manganese(II) minerals]]
[[Category:Symbols of Colorado]]
[[Category:Trigonal minerals]]
[[Category:Minerals in space group 167]]
[[Category:National symbols of Argentina]]