Editing Thorite

{{Short description|Nesosilicate mineral}}
{{infobox mineral
|boxbgcolor=#926339| name = Thorite
| boxtextcolor = #fff
| image = Thorite-288916.jpg
| imagesize   = 260px
| caption = Thorite crystal from the Kemp uranium mine in Ontario (size: 2.2 x 2.2 x 1.6 cm)
| category    = [[Silicate mineral]]
| formula     = (Th,U)SiO<sub>4</sub>
| IMAsymbol   = Thr<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      = 9.AD.30
| dana        = 
| system      = [[Tetragonal crystal system|Tetragonal]]
| class       = Ditetragonal dipyramidal (4/mmm) <br/>[[H-M symbol]]: (4/m 2/m 2/m)
| symmetry    = ''I''4<sub>1</sub>/amd 
| unit cell   = a = 7.13, c = 6.32&nbsp;[Å]; Z&nbsp;=&nbsp;4
| color       = Yellow-orange, brownish yellow, brownish black, black, green
| colour      = 
| habit       = In square prisms, or pseudo-octahedral crystals; also massive
| twinning    = 
| cleavage    = Distinct on {110}
| fracture    = Conchoidal
| tenacity    = Brittle
| mohs        = 4.5 – 5
| luster      = Vitreous to resinous
| streak      = Light orange to light brown sometimes even an alien magenta
| diaphaneity = Nearly opaque, transparent in thin fragments
| gravity     = 6.63 – 7.20
| density     = 
| polish      = 
| opticalprop = Uniaxial (−)
| refractive  = n<sub>ω</sub> = 1.790 – 1.840 n<sub>ε</sub> = 1.780 – 1.820
| birefringence = δ = 0.010 – 0.020
| pleochroism = 
| 2V          = 
| dispersion  = 
| extinction  = 
| length fast/slow =
| fluorescence = 
| absorption  = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| impurities  = 
| alteration  = Commonly metamict
| other       = [[Image:Radioactive.svg|25px]] [[Radioactive]]
| prop1       = 
| prop1text   = 
| references = <ref name=Webmin>[http://webmineral.com/data/Thorite.shtml Webmineral data]</ref><ref name=Mindat>[http://www.mindat.org/min-3946.html Mindat.org]</ref><ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/thorite.pdf Handbook of Mineralogy]</ref>
}}
'''Thorite''', (Th,U)SiO<sub>4</sub>, is a rare [[Silicate minerals|nesosilicate]] of [[thorium]] that [[crystal]]lizes in the [[tetragonal]] system and is [[Isomorphism (crystallography)|isomorphous]] with [[zircon]] and [[hafnon]]. It is the most common [[mineral]] of [[thorium]] and is nearly always strongly [[Radioactivity|radioactive]]. Thorite was discovered in 1828 on the island of [[Løvøya, Telemark|Løvøya]], Norway, by the vicar and mineralogist, [[Morten Thrane Esmark|Hans Morten Thrane Esmark]]. First specimens of Thorite were sent to his father, [[Jens Esmark]], who was a professor of mineralogy and geology.<ref>{{cite journal | doi = 10.1080/14786442908675174 | title = Thorite, a new mineral, and thorina, a new earth | year = 1829 | last1 = Berzelius | first1 = M. | journal = Philosophical Magazine |series=Series 2 | volume = 6 | issue = 35 | pages = 392–393| url = https://zenodo.org/record/1430987 }}</ref><ref>{{cite journal | doi = 10.1002/andp.18290920702 | title = Untersuchung eines neuen Minerals und einer darin enthaltenen zuvor unbekannten Erde | year = 1829 | last1 = Berzelius | first1 = J. J. | journal = Annalen der Physik und Chemie | volume = 92 | issue = 7 | pages = 385–415 |bibcode = 1829AnP....92..385B | url = https://zenodo.org/record/1423530 }}</ref><ref>{{cite journal | last1 = Marshall | first1 = J.L. | last2 = Marshall | first2 = V.R. | year = 2001 | title = Rediscovery of the Elements- Thorium-Løvøya, Langesundsfjord, Norway | journal = The Hexagon | volume = 93 | pages = 70–73 | url = http://www.chem.unt.edu/Rediscovery/Thorium.pdf | url-status = dead | archiveurl = https://web.archive.org/web/20050408114055/http://www.chem.unt.edu/Rediscovery/Thorium.pdf | archivedate = 2005-04-08 }}
</ref> It was named in 1829 to reflect its [[thorium]] content.

==Occurrence==

[[File:Thorit 1.jpg|thumb|left|Thorite in Prague national museum]]
[[File:Thorites - CAMR www.amrminerals.co.uk 10-crop.jpg|thumb|left|Small crystals of green thorite under magnification]]

Specimens of thorite generally come from [[igneous rock|igneous]] [[pegmatite]]s and [[volcanic]] extrusive rocks, hydrothermal veins and contact [[metamorphic rock]]s. It is also known to occur as small grains in detrital sands. Crystals are rare, but when found can produce nicely shaped short prismatic crystals with pyramidal terminations.
It is commonly associated with [[zircon]], [[monazite]], [[gadolinite]], [[fergusonite]], [[uraninite]], [[yttrialite]] and [[pyrochlore]].<ref name=HBM/>

Thorite is currently an important ore of [[uranium]]. A variety of thorite, often called "uranothorite", is particularly rich in uranium and has been a viable uranium ore at Bancroft in [[Ontario]], Canada. Other varieties of thorite include "orangite", an orange variety, and "calciothorite", an impure variety with trace amounts of [[calcium]].

==Properties==
Due to the radioactive elements contained, Thorite is commonly ''[[Metamictisation|metamict]]''. With the destructive effects of radioactivity on the [[crystal lattice]], hydrated specimens are often [[amorphous]] and optically isotropic. 
Owing to differences in composition, the [[specific gravity]] varies from 4.4 to 6.6 g/cm<sup>3</sup>. Hardness is 4.5 and the luster is vitreous or resinous. The color is normally black, but can range from brownish black to orange, yellowish-orange and dark green.

==References==
{{Reflist}}

==External links==
{{Commons category|Thorite}}
{{EB1911 poster|Thorite}}

[[Category:Thorium minerals]]
[[Category:Uranium(IV) minerals]]
[[Category:Nesosilicates]]
[[Category:Radioactive gemstones]]
[[Category:Tetragonal minerals]]
[[Category:Minerals in space group 141]]
[[Category:Minerals described in 1829]]