View source for Chemistry:Cassiterite

{{short description|Tin oxide mineral, SnO₂}}
{{Infobox mineral
| name        = Cassiterite
| category    = [[Chemistry:Oxide minerals|Oxide minerals]]
| boxwidth    =
| boxbgcolor  =
| image       = 4447M-cassiterite.jpg
| imagesize   =
| caption     = Cassiterite with [[Chemistry:Muscovite|muscovite]], from Xuebaoding, Huya, Pingwu, Mianyang, Sichuan, China (size: 100 x 95 mm, 1128 g)
| formula     = SnO<sub>2</sub>
| IMAsymbol=Cst<ref>{{Cite journal|last=Warr|first=L.N.|date=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   =
| strunz      = 4.DB.05
| system      = Tetragonal 
| class       = Ditetragonal dipyramidal (4/mmm) <br/>[[Chemistry:H-M symbol|H-M symbol]]: (4/m 2/m 2/m)
| symmetry    = ''P4''<sub>2</sub>/mnm
| unit cell   = a = 4.7382(4)&nbsp;Å, <br/>c = 3.1871(1)&nbsp;Å; Z&nbsp;=&nbsp;2
| color       = Black, brownish black, reddish brown, brown, red, yellow, gray, white; rarely colorless 
| habit       = Pyramidic, prismatic, radially fibrous botryoidal crusts and concretionary masses; coarse to fine granular, massive
| twinning    = Very common on {011}, as contact and penetration twins, geniculated; lamellar
| cleavage    = {100} imperfect, {110} indistinct; partings on {111} or {011}
| fracture    = Subconchoidal to uneven
| tenacity    = Brittle
| mohs        = 6–7
| luster      = Adamantine to adamantine metallic, splendent; may be greasy on fractures
| refractive  = n<sub>ω</sub> = 1.990–2.010 n<sub>ε</sub> = 2.093–2.100
| opticalprop = Uniaxial (+)
| birefringence = δ = 0.103
| pleochroism = Pleochroic haloes have been observed. Dichroic in yellow, green, red, brown, usually weak, or absent, but strong at times
| streak      = White to brownish
| gravity     = 6.98–7.1
| density     =
| melt        =
| fusibility  = infusible
| diagnostic  =
| solubility  = insoluble
| diaphaneity = Transparent when light colored, dark material nearly opaque; commonly zoned
| other       =
| references  = <ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Cassiterite Mineralienatlas]</ref><ref name=Handbook>{{cite web |last1=Anthony |first1=John W. |last2=Bideaux |first2=Richard A. |last3=Bladh |first3=Kenneth W. |last4=Nichols |first4=Monte C. |title=Cassiterite |url=http://www.handbookofmineralogy.org/pdfs/cassiterite.pdf |website=Handbook of Mineralogy |publisher=Mineral Data Publishing |access-date=19 June 2022 |date=2005}}</ref><ref name=Mindat>{{mindat|id=917|title=Cassiterite}}</ref><ref name=Webmin>[http://webmineral.com/data/Cassiterite.shtml Webmineral]</ref><ref name=Klein>{{cite book |last1=Hurlbut |first1=Cornelius S. |last2=Klein |first2=Cornelis |year=1985 |title=Manual of Mineralogy |edition=20th |publisher=John Wiley and Sons |location=New York |pages=[https://archive.org/details/manualofmineralo00klei/page/306 306–307] |isbn=0-471-80580-7 |url-access=registration |url=https://archive.org/details/manualofmineralo00klei/page/306 }}</ref>
}}
'''Cassiterite''' is a [[Chemistry:Tin|tin]] [[Chemistry:Oxide mineral|oxide mineral]], SnO<sub>2</sub>.  It is generally [[Physics:Opacity (optics)|opaque]], but it is translucent in thin crystals. Its [[Earth:Lustre (mineralogy)|luster]] and multiple crystal faces produce a desirable gem. Cassiterite was the chief tin [[Earth:Ore|ore]] throughout [[Chemistry:Tin sources and trade in ancient times|ancient history]] and remains the most important source of tin today.

==Occurrence==
[[File:Cassiterite.jpg|thumb|left|Cassiterite bipyramids, edge length ca. 30 mm, Sichuan, China]]
[[Image:Cassiterite - Blue Tier tinfield, Tasmania, Australia.jpg|thumb|left|Close up of cassiterite crystals, Blue Tier tinfield, Tasmania, Australia]]

Most sources of cassiterite today are found in [[Earth:Alluvium|alluvial]] or [[Earth:Placer mining|placer]] deposits containing the weathering-resistant grains. The best sources of primary cassiterite are found in the tin mines of Bolivia, where it is found in crystallised hydrothermal veins. [[Biology:Rwanda|Rwanda]] has a nascent cassiterite mining industry. Fighting over cassiterite deposits (particularly in Walikale) is a major cause of the conflict waged in eastern parts of the Democratic Republic of the Congo.<ref>{{cite news |url=http://www.newsvine.com/_news/2008/11/01/2061627-mining-for-minerals-fuels-congo-conflict|title=Mining for minerals fuels Congo conflict |last=Watt |first=Louise |agency=Associated Press |date=2008-11-01 |access-date=2009-09-03|work=Yahoo! News |publisher=[[Company:Yahoo!|Yahoo! Inc]]}}</ref><ref>{{cite news
 | last = Polgreen
 | first = Lydia
 | title = Congo's Riches, Looted by Renegade Troops
 | work={{wipe|The New York Times}}
 | date = 2008-11-16
 | url = https://www.nytimes.com/2008/11/16/world/africa/16congo.html?pagewanted=1&_r=1&th&emc=th
 | access-date = 2008-11-16}}</ref>  This has led to cassiterite being considered a conflict mineral.

Cassiterite is a widespread minor constituent of igneous rocks. The Bolivian veins and the 4500 year old workings of [[History:Cornwall|Cornwall]] and [[Earth:Devon|Devon]], {{wipe|England}}, are concentrated in high temperature [[Chemistry:Quartz|quartz]] veins and [[Earth:Pegmatite|pegmatite]]s associated with [[Chemistry:Granite|granitic]] [[Earth:Intrusive rock|intrusive]]s. The veins commonly contain [[Chemistry:Tourmaline|tourmaline]], [[Chemistry:Topaz|topaz]], [[Chemistry:Fluorite|fluorite]], [[Chemistry:Apatite|apatite]], [[Chemistry:Wolframite|wolframite]], [[Chemistry:Molybdenite|molybdenite]], and [[Chemistry:Arsenopyrite|arsenopyrite]]. The mineral occurs extensively in [[History:Cornwall|Cornwall]] as surface deposits on Bodmin Moor, for example, where there are extensive traces of a hydraulic mining method known as ''streaming''. The current major tin production comes from placer or alluvial deposits in Malaysia, Thailand, Indonesia, the Maakhir region of Somalia, and {{wipe|Russia}}. [[Engineering:Hydraulic mining|Hydraulic mining]] methods are used to concentrate mined ore, a process which relies on the high [[Physics:Specific gravity|specific gravity]] of the SnO<sub>2</sub> ore, of about 7.0.

==Crystallography==
[[Image:Rutile-unit-cell-3D-balls.png|thumb|left|Crystal structure of cassiterite]]

[[Physics:Crystal twinning|Crystal twinning]] is common in cassiterite and most aggregate specimens show crystal twins. The typical twin is bent at a near-60-degree angle, forming an "elbow twin". Botryoidal or reniform cassiterite is called ''wood tin''.

Cassiterite is also used as a [[Earth:Gemstone|gemstone]] and collector specimens when quality crystals are found.

[[File:Cassiterite-43265.jpg|thumb|upright|left|Stalactitic-botryoidal, banded, "wood tin" cassiterite, 5.0 × 4.9 × 3.3 cm, Durango, Mexico]]

==Etymology==
The name derives from the [[Social:Greek language|Greek]] ''kassiteros'' for "tin": this comes from the Phoenician word ''Cassiterid'' referring to the islands of Ireland and Great Britain,{{cn|date=October 2022}} the ancient sources of tin; or, as Roman Ghirshman (1954) suggests, from the region of the Kassites, an ancient people in west and central [[Religion:Iran|Iran]].

{{clear}}

== Use ==
It may be primary used as a raw material for [[Chemistry:Tin|tin]] extraction and smelting.

==References==
{{reflist|25em}}

==External links==

{{Ores}}


[[Category:Tin minerals]]
[[Category:Oxide minerals]]
[[Category:Tetragonal minerals]]

{{Sourceattribution|Cassiterite}}