Editing Autunite (section)

{{Short description|Type of phosphate mineral}}
{{Infobox mineral
| name        = Autunite
| boxwidth    = 
| boxbgcolor  =#d2d75e 
| image       = Autunite-69257.jpg
| imagesize   = 
| alt         = 
| caption     = Autunite from Daybreak Mine, Washington
| category    = [[Phosphate minerals]]
| formula     = Ca(UO<sub>2</sub>)<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>·10–12H<sub>2</sub>O
|IMAsymbol=Aut<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   = 986.26 g/mol
| strunz      = 8.EB.05
| dana        = 
| system      = [[Orthorhombic crystal system|Orthorhombic]]
| class       = Dipyramidal (mmm) <br/>[[H-M symbol]]: (2/m 2/m 2/m)
| symmetry    = ''Pnma'' 
| unit cell   = a = 14.0135(6), <br/>b = 20.7121(8), <br/>c = 6.9959(3)&nbsp;[Å]; Z&nbsp;=&nbsp;4
| color       = Lemon-yellow to sulfur-yellow, greenish yellow to pale green; may be dark green to greenish black 
| colour      = 
| habit       = Tabular crystals, foliated or scaly aggregates, and in crusts
| twinning    = Rare on {110}
| cleavage    = {001} perfect, {100} and {010} poor 
| fracture    = uneven
| tenacity    = 
| mohs        = 2–2.5 
| luster      = Vitreous – pearly
| streak      = Pale yellow
| diaphaneity = Transparent to translucent
| gravity     = 3.1–3.2
| density     = 3.15 
| polish      = 
| opticalprop = Biaxial (−)
| refractive  = n<sub>α</sub> = 1.553 – 1.555 n<sub>β</sub> = 1.575 n<sub>γ</sub> = 1.577 – 1.578 
| birefringence = δ = 0.003
| pleochroism = X = colorless to pale yellow; Y = Z = yellow to dark yellow
| 2V          = Measured: 10° to 53°
| dispersion  = 
| extinction  = 
| length fast/slow =
| fluorescence = Strong yellow-green fluorescence in UV; Radioactive
| absorption  = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = Soluble in acids
| impurities  = 
| alteration  = Dehydrates in air
| other       = Pseudotetragonal for synthetic material, [[Image:Radioactive.svg|25px]] [[Radioactive]]
| references  = <ref name=Mindat>[http://www.mindat.org/min-433.html Mindat.org]</ref><ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/autunite.pdf Handbook of Mineralogy]</ref>
}}

'''Autunite''' (hydrated calcium uranyl phosphate), with formula Ca(UO<sub>2</sub>)<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>·10–12H<sub>2</sub>O, is a yellow-greenish [[fluorescence|fluorescent]] [[Phosphate minerals|phosphate]] [[mineral]] with a [[Mohs scale of mineral hardness|hardness]] of 2–{{frac|2|1|2}}.<ref>{{Cite web|url=http://webmineral.com/data/Autunite.shtml|title=Autunite Mineral Data|last=Barthelmy|first=Dave|website=webmineral.com|access-date=2018-01-26}}</ref><ref name=":0">{{Cite web|url=https://www.mindat.org/min-433.html|title=Autunite: Autunite mineral information and data.|website=www.mindat.org|access-date=2018-04-28}}</ref> Autunite crystallizes in the [[Orthorhombic crystal system|orthorhombic]] system and often occurs as tabular square [[crystal]]s, commonly in small crusts or in fan-like masses. Due to the moderate [[uranium]] content of 48.27% it is [[Radioactive decay|radioactive]] and also used as uranium ore. Autunite fluoresces bright green to lime green under UV light. The mineral is also called '''calco-uranite''', but this name is rarely used and effectively outdated.<ref name=":1">{{cite EB1911|wstitle=Autunite |volume= 03 |short= x}}</ref>

Autunite was discovered in 1852 near [[Autun]], [[France]], which is also autunite's namesake. It occurs as an [[redox|oxidation]] product of uranium minerals in [[granite]] [[pegmatite]]s and [[hydrothermal circulation|hydrothermal]] deposits. Associate minerals include [[metaautunite]], [[torbernite]], [[phosphuranylite]], [[saleeite]], [[uranophane]] and [[sabugalite]].<ref name=HBM/>