# Torbernite

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{{Short description|Copper uranyl phosphate mineral}}
{{Distinguish|Tobermorite|Torbanite}}

{{Infobox mineral
| name        = Torbernite
| category    = [Phosphate minerals](/source/Phosphate_minerals)
| boxwidth    = 
| boxbgcolor  =#40a160
| image       = Torbernite-120981.jpg
| imagesize   = 260px
| caption     = Torbernite crystals from Mashamba West Mine, [Kolwezi](/source/Kolwezi), [Katanga Province](/source/Katanga_Province), [Democratic Republic of the Congo](/source/Democratic_Republic_of_the_Congo)
| formula     = Cu[(UO<sub>2</sub>)(PO<sub>4</sub>)]<sub>2</sub>(H<sub>2</sub>O)<sub>12</sub><ref name="LocockBurns" />
| IMAsymbol   = Tor<ref name="Warr" />
| molweight   = 641 – 713 g/mol, depending the degree of water loss
| strunz      = 8.EB.05
| system      = Tetragonal
| class       = Ditetragonal dipyramidal (4/mmm) <br/>[H-M symbol](/source/H-M_symbol): (4/m 2/m 2/m)<ref name="Webmineral" />
| symmetry    = ''I4/mmm''<ref name="StrunzNickel" />
| color       = Emerald green to apple green<ref name="Handbookofmineralogy" />
| habit       = Tabular crystals; Foliated to earthy masses and encrustations
| twinning    = Rare on [110]
| cleavage    = [001] Perfect; [100] Distinct<ref name="Handbookofmineralogy" />
| fracture    = Brittle<ref name="Handbookofmineralogy" />
| mohs        = 2–2.5<ref name="Handbookofmineralogy" />
| luster      = Vitreous; pearly<ref name="Handbookofmineralogy" />
| refractive  = nω = 1.590 – 1.592 nε = 1.581 – 1.582<ref name="Webmineral" />
| opticalprop = Uniaxial (−)
| birefringence = δ = 0.009 – 0.010<ref name="Webmineral" />
| pleochroism = Visible
| streak      = Pale green
| density     = measured: 3.22; calculated: 3.264(1)<ref name="Handbookofmineralogy" />
| melt        = Decomposes before
| fusibility  = Decomposes before
| diagnostic  = 
| solubility  = 
| diaphaneity = Transparent to subtranslucent
| other       = 25px [Radioactive](/source/Radioactive) and [Poisonous](/source/Poisonous) 30px
| references  = 
}}

'''Torbernite''', also known as '''chalcolite''',<ref name="Klockmann" />  is a relatively common [mineral](/source/mineral) with the chemical formula Cu[(UO<sub>2</sub>)(PO<sub>4</sub>)]<sub>2</sub>·12H<sub>2</sub>O.<ref name="LocockBurns" /> It is a [radioactive](/source/radioactive), [hydrate](/source/hydrate)d green [copper](/source/copper) [uranyl](/source/uranyl) [phosphate](/source/phosphate), found in [granite](/source/granite)s and other uranium-bearing deposits as a secondary mineral. 
The chemical formula of torbernite is similar to that of [autunite](/source/autunite) in which a Cu<sup>2+</sup> cation replaces a Ca<sup>2+</sup> cation. Torbernite tends to [dehydrate](/source/Dehydration_reaction) to [metatorbernite](/source/metatorbernite) with the sum formula Cu[(UO<sub>2</sub>)(PO<sub>4</sub>)]<sub>2</sub>·8H<sub>2</sub>O.

== Etymology and history ==
thumb|left|Torbern Olof Bergman
Torbernite was found for the first time at Georg Wagsfort Mine near [Johanngeorgenstadt](/source/Johanngeorgenstadt) in the [Ore Mountains](/source/Ore_Mountains) in Saxony. It was first mentioned in 1772 by [Ignaz von Born](/source/Ignaz_von_Born) in his work ''Lythophylacium Bornianum'', calling it "mica viridis crystallina, ibid." (green crystalline mica from Johanngeorgenstadt, Sax.; ''ibid.'' = "as the item above"). In 1780 [Abraham Gottlob Werner](/source/Abraham_Gottlob_Werner) uses Born's work and describes the mineral in more detail, calling it at first "grüner Glimmer" (green mica), later naming it "torbernite" in honour of the Swedish mineralogist and chemist [Torbern Olof Bergman](/source/Torbern_Olof_Bergman) (1735–1784).<ref name="strahlen.org" />

== Classification ==
According to the [International Mineralogical Association](/source/International_Mineralogical_Association) (IMA), which last updated its list in 2009,<ref name="IMA-Liste-2009" /> the Nickel-Strunz system lists torbernite in the section of "uranyl phosphates and arsenates". There it is part of the sub-section "UO<sub>2</sub>&nbsp;:&nbsp;RO<sub>4</sub>&nbsp;=&nbsp;1&nbsp;:&nbsp;1", forming the autunite group along with [autunite](/source/autunite), [heinrichite](/source/heinrichite), [kahlerite](/source/kahlerite), [kirchheimerite](/source/kirchheimerite), [metarauchite](/source/metarauchite), [nováčekite-I](/source/nov%C3%A1%C4%8Dekite-I), [nováčekite-II](/source/nov%C3%A1%C4%8Dekite-II), [saléeite](/source/sal%C3%A9eite), [uranocircite I](/source/uranocircite_I), [uranocircite II](/source/uranocircite_II), [uranospinite](/source/uranospinite), [xiangjiangite](/source/xiangjiangite) and [zeunerite](/source/zeunerite) with system number ''8.EB.05''.

Dana groups the mineral into the class "phosphates, arsenates and vanadates", into the section "hydrated phosphates etc." into an unnamed group with [metatorbernite](/source/metatorbernite), number 40.02a.13.

== Crystal structure ==
[[Image:Torbernite - packing.png|thumb|left|Packing of torbernite. Colour code: <span style="color: green">[uranium](/source/uranium)</span>, <span style="color: lime">[copper](/source/copper)</span>, <span style="color: yellow">[phosphorus](/source/phosphorus)</span>, <span style="color: red">[oxygen](/source/oxygen)</span>, <span style="color: grey">[water](/source/water)</span>, <span style="color: silver">[hydrogen](/source/hydrogen)</span>]]

Torbernite crystallises in the tetragonal [space group](/source/space_group) ''I''4/''mmm'' with the lattice parameters ''a''&nbsp;=&nbsp;7.0267(4)&nbsp;Å und ''c''&nbsp;=&nbsp;20.807(2)&nbsp;Å and 2 formula units per unit cell.<ref name="LocockBurns" />

In a study in 2003, using fresh, synthetic crystals, Locock and Burns have compared the crystal structures of the copper uranyl phosphates torbernite, Cu[(UO<sub>2</sub>)(PO<sub>4</sub>)]<sub>2</sub>(H<sub>2</sub>O)<sub>12</sub> and metatorbernite, Cu[(UO<sub>2</sub>)(PO<sub>4</sub>)]<sub>2</sub>(H<sub>2</sub>O)<sub>8</sub> with those of the copper uranyl [arsenate](/source/arsenate)s zeunerite, Cu[(UO<sub>2</sub>)(AsO<sub>4</sub>)]<sub>2</sub>(H<sub>2</sub>O)<sub>12</sub>, and metazeunerite, Cu[(UO<sub>2</sub>)(AsO<sub>4</sub>)]<sub>2</sub>(H<sub>2</sub>O)<sub>8</sub>. In these studies they were able to finally analyse the crystal structure of torbernite for the very first time, and to get a significantly more precise analysis for the structure of metatorbernite, compared with previous studies (Makarov and Tobelko [''R''1](/source/R-factor_(crystallography)) = 25%,<ref name="Makarov" /> Ross et al. ''R''1 = 9.7%,<ref name="Ross" /> Stergiou et al. ''R''1 = 5.6%,<ref name="Stergiou" /> Calos and Kennard ''R''1 = 9.2%<ref name="Calos" /> vs. Locock und Burns ''R''1 = 2.3%).

The study shows that torbernite is [isostructural](/source/isostructural) to zeunerite, and metatorbernite is isostructural to metazeunerite. All four compounds are of the layered autunite type with the [(UO<sub>2</sub>)(XO<sub>4</sub>)]<sup>−</sup> structural motif (with X = P or As). The Cu<sup>2+</sup> ions are coordinated in a square-planar fashion by water molecules in all these compounds, and further coordinate to the uranyl oxygen atoms, forming octahedra with [Jahn-Teller distortion](/source/Jahn%E2%80%93Teller_effect). The additional water molecules are held in the crystal structure only by [hydrogen bridges](/source/Hydrogen_bond).

== Metatorbernite ==
[[Image:Metatorbernite sapin.jpg|thumb|[Metatorbernite](/source/Metatorbernite) from [Margabal Mine](/source/Margabal_Mine), [Entraygues-sur-Truyère](/source/Entraygues-sur-Truy%C3%A8re), France (Size:&nbsp;4&nbsp;cm&nbsp;×&nbsp;3&nbsp;cm&nbsp;×&nbsp;1.8&nbsp;cm)]]
Torbernite dehydrates readily to metatorbernite with the sum formula Cu[(UO<sub>2</sub>)(PO<sub>4</sub>)]<sub>2</sub>(H<sub>2</sub>O)<sub>8</sub>. It forms as torbernite withers, and can also be obtained by artificially heating torbernite above 75&nbsp;°C.<ref name="Hallimond1916" /> The crystals are rather opaque and only weakly translucent with a glassy lustre.<ref name="MindatMeta" />

Metatorbernite crystallises tetragonally-dipyramidally in space group ''P''4/''n'' with the lattice parameters ''a''&nbsp;=&nbsp;6.9756(5)&nbsp;Å and ''c''&nbsp;=&nbsp;17.349(2)&nbsp;Å and 2 formula units per unit cell.<ref name="LocockBurns" />

thumb|Packing of metatorbernite. Colour code: <span style="color: green">uranium</span>, <span style="color: lime">copper</span>, <span style="color: yellow">phosphorus</span>, <span style="color: red">oxygen</span>, <span style="color: grey">water</span>, <span style="color: silver">hydrogen</span>

The crystal structure of metatorbernite is different from torbernite as every second uranyl phosphate layer is moved about one half of the length of the crystallographic ''a''-axis in the [directions](/source/Miller_index) [100] and [010].<ref name="LocockBurns" /> The analysis by Locock and Burns confirms the finding by Stergiou et al., that the Cu<sup>2+</sup> ions only have an 88% crystallographic occupancy. The authors assume that by protonation of some of the water molecules there is a charge compensation for electronic neutrality, as it is discussed with the mineral [chernikovite](/source/chernikovite).<ref name="LocockBurns" /> The same is postulated by the same authors for autunite.<ref name="LocockBurnsAutunit" /> Due to the limitations of [X-ray diffraction](/source/X-ray_crystallography) this postulate is practically not verifiable with this method.

The analysis by Locock and Burns shows eight molecules of water per formula unit in metatorbernite. This is in accord with the works by Arthur Francis Hallimons<ref name="Hallimond1916" /><ref name="Hallimond1920" /> and [Kurt Walenta](/source/Kurt_Walenta),<ref name="Walenta" /> who show that the different steps of hydration between torbernite and metatorbernite have clear boundaries, and the water content of each compound remains constant and does not vary, in contrast for instance, as seen in minerals of the [zeolite](/source/zeolite) group. Therefore, sum formulae indicating varying degrees of water for torbernite and metatorbernite must not be used.<ref name="LocockBurns" />

== Properties ==
thumb|A pyramidal torbernite crystal from Brest, France<br>(Field of view: 7&nbsp;mm × 5&nbsp;mm)
thumb|Intergrowth of dipyramidal crystals of metatorbernite in a geode from Les Montmins Mine (Ste Barbe Ader), Échassières, Kanton Ébreuil, Département Allier, Auvergne, France (Field of view: 1&nbsp;mm × 1&nbsp;mm)

=== Morphology ===
The mineral is often encountered as small thin tabular crystals, but may also be flaky or powdery. More rare are thicker plates, resembling a stacked deck of cards. More frequent than these are dipyramidal forms.

=== Physical and chemical properties ===
Because of its uranium content of about 48% the material is strongly [radioactive](/source/Radioactive_decay). According to the sum formula a specific activity of 85.9&nbsp;k[Bq](/source/Becquerel)/g<ref name="Webmineral" /> can be given (for comparison: natural [potassium](/source/potassium): 0.0312&nbsp;kBq/g).

Contrary to its calcium analogue autunite the mineral does not fluoresce.<ref name="Klockmann" /> 
The mineral is very brittle. Its hardness (Mohs) is between 2 and 2.5.

== Occurrence and localities ==
[[Image:Wulfenite-Kasolite-Torbernite-214957.jpg|thumb|[Paragenesis](/source/Paragenesis) of [kasolite](/source/kasolite) (yellow, acicular) with torbernite (green, platy)]]
Torbernite forms as a secondary mineral on the oxidation zone of uranium ores. It is often found in paragenesis with [autunite](/source/autunite), [metatorbernite](/source/metatorbernite), [uraninite](/source/uraninite), [zeunerite](/source/zeunerite) and, very rarely, with [gauthierite](/source/gauthierite).<ref name="Olds" />

Torbernite is relatively common, and world-wide there are more than 1100 documented localities known by 2022.<ref name="MindatAnzahl" /> In Germany it is known not only from its type locality Johanngeorgenstadt, but also from other areas in the [Ore Mountains](/source/Ore_Mountains), as well as from the Black Forest, [Fichtel Mountains](/source/Fichtel_Mountains), [Bavarian Forest](/source/Bavarian_Forest), [Thuringian Forest](/source/Thuringian_Forest). Further localities are in [Argentina](/source/Argentina), [Australia](/source/Australia), [Austria](/source/Austria), [Belgium](/source/Belgium), [Bolivia](/source/Bolivia), [Brazil](/source/Brazil), [Canada](/source/Canada), [Chile](/source/Chile), [China](/source/China), [Czech Republic](/source/Czech_Republic), [Democratic Republic of the Congo](/source/Democratic_Republic_of_the_Congo), [France](/source/France), [Gabon](/source/Gabon), [Ireland](/source/Republic_of_Ireland), [Italy](/source/Italy), [Japan](/source/Japan), [Madagascar](/source/Madagascar), [Mexico](/source/Mexico), [Namibia](/source/Namibia), [Norway](/source/Norway), [Poland](/source/Poland), [Portugal](/source/Portugal), [Romania](/source/Romania), [Slovakia](/source/Slovakia), [Slovenia](/source/Slovenia), [Spain](/source/Spain), [South Africa](/source/South_Africa), [Switzerland](/source/Switzerland), [Tajikistan](/source/Tajikistan), [Uzbekistan](/source/Uzbekistan), the [United Kingdom](/source/United_Kingdom) and the [United States](/source/United_States).<ref name="Fundorte" />

== Precautions ==
thumb|A torbernite specimen from the Margabal Mine in the Midi-Pyrénées, France
Because of the inherent toxicity of uranium compounds, samples of this mineral should be kept in air tight glass jars.

==See also==
* [List of minerals](/source/List_of_minerals)
* [List of minerals named after people](/source/List_of_minerals_named_after_people)

==References==
<references>
<ref name="Calos">
N. J. Calos, C. H. L. Kennard: ''Crystal structure of copper bis(uranyl phosphate) octahydrate (metatorbernite), Cu(UO<sub>2</sub>PO<sub>4</sub>)<sub>2</sub>·8(H<sub>2</sub>O)'' In: ''Zeitschrift für Kristallographie'' 1996, ''211'', 701–702 ([https://rruff.info/doclib/zk/vol211/ZK211_701.pdf PDF 85.1 kB]) 
</ref>
<ref name="Fundorte">
List of localities for torbernite at [https://www.mineralienatlas.de/lexikon/index.php/MineralDataShow?mineralid=3881&sections=12 Mineralienatlas] (German) and at [https://www.mindat.org/min-3997.html#autoanchor25 Mindat] (English).
</ref>
<ref name="Warr">
L. N. Warr: ''IMA–CNMNC approved mineral symbols'' In: ''[Mineralogical Magazine](/source/Mineralogical_Magazine)'' 2021, ''85'' 291–320 ([https://www.cambridge.org/core/services/aop-cambridge-core/content/view/62311F45ED37831D78603C6E6B25EE0A/S0026461X21000438a.pdf/imacnmnc-approved-mineral-symbols.pdf PDF 320 kB]) 
</ref>
<ref name="Hallimond1916">
A. F. Hallimond: ''The crystallography and dehydration of torbernite'' In: ''[Mineralogical Magazine](/source/Mineralogical_Magazine)'' 1916, ''17'' (82), 326–339 ([https://rruff.info/doclib/MinMag/Volume_17/17-82-326.pdf PDF 559 kB])
</ref>
<ref name="Hallimond1920">
A. F. Hallimond: ''Meta-torbernite I. Its physical properties and relation to torbernite'' In: ''[Mineralogical Magazine](/source/Mineralogical_Magazine)'' 1920, ''19'' (89), 43–47 ([https://rruff.info/doclib/MinMag/Volume_19/19-89-43.pdf PDF 228 kB])
</ref>
<ref name="Handbookofmineralogy">
J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols (Eds.): ''Torbernite'' In: ''Handbook of Mineralogy'', Mineralogical Society of America 2001 ([https://www.handbookofmineralogy.org/pdfs/Torbernite.pdf PDF 63 kB])
</ref>
<ref name="IMA-Liste-2009">
[E. H. Nickel](/source/Ernest_Henry_Nickel), M. C. Nichols: ''IMA/CNMNC List of Minerals 2009'' ( http://cnmnc.main.jp/IMA2009-01%20UPyear%20160309.pdf PDF 1.82 MB])
</ref>
<ref name="Klockmann">
F. Klockmann: ''Klockmanns Lehrbuch der Mineralogie'' 1978, ''16'', Enke, Stuttgart, 655 pages. {{ISBN|3-432-82986-8}}</ref>
<ref name="LocockBurns">
A. J. Locock, P. C. Burns: ''Crystal structures and synthesis of the copper-dominant members of the autunite and meta-autunite groups: torbernite, zeunerite, metatorbernite and metazeunerite'' In: ''The Canadian Mineralogist'' 2003, ''41'', 489–502 ([https://rruff.info/rruff_1.0/uploads/CM41_489.pdf PDF 2500 kB])
</ref>
<ref name="LocockBurnsAutunit">
A. J. Locock, P. C. Burns: ''The crystal structure of synthetic autunite, Ca[(UO<sub>2</sub>)(PO<sub>4</sub>)]<sub>2</sub>(H<sub>2</sub>O)<sub>11</sub>'' In: ''American Mineralogist'' 2003, ''88'', 240–244 ([https://rruff.info/doclib/am/vol88/AM88_240.pdf PDF 408 kB])
</ref>
<ref name="Makarov">
E. S. Makarov, K. I. Tobelko: ''Crystal structure of metatorbernite'' In: ''Doklady Akademii Nauk SSSR'' 1960, ''131'', 87–89
</ref>
<ref name="MindatAnzahl">
{{cite web|date=2022-10-10|language=en|publisher=Hudson Institute of Mineralogy|title=Localities for Torbernite|url=https://www.mindat.org/min-3997.html#autoanchor24|website=mindat.org}}<!-- auto-translated by Module:CS1 translator -->
</ref>
<ref name="MindatMeta">
{{cite web|date=2022-10-10|language=en|publisher=Hudson Institute of Mineralogy|title=Metatorbernite|url=https://www.mindat.org/min-2689.html|website=mindat.org}}<!-- auto-translated by Module:CS1 translator -->
</ref> 
<ref name="Ross">
M. Ross, H. T. Evans Jr., D. E. Appleman: ''Studies of the torbernite minerals. II. The crystal structure of metatorbernite'' In: ''American Mineralogist'' 1964, ''49'', 1603–1621 ([http://www.minsocam.org/ammin/AM49/AM49_1603.pdf PDF 1126 kB])
</ref>
<ref name="Stergiou">
A. C. Stergiou, P. J. Rentzeperis, S. Sklavounos: ''Refinement of the crystal structure of metatorbernite'' In: ''Zeitschrift für Kristallographie'' 1993, ''205'' 1–7 ([https://rruff.info/uploads/ZK205_1.pdf PDF 391 kB])
</ref>
<ref name="StrunzNickel">
[K. H. Strunz](/source/Karl_Hugo_Strunz), [E. H. Nickel](/source/Ernest_Henry_Nickel): ''Strunz Mineralogical Tables. Chemical-structural Mineral Classification System'' 2001, ''9'', E. Schweizerbart’sche Verlagsbuchhandlung (Nägele u. Obermiller), Stuttgart, 524 pages. {{ISBN|3-510-65188-X}}
</ref>
<ref name="strahlen.org">
{{cite web|author=T. Witzke|title=Entdeckung von Torbernit|url=https://www.strahlen.org/tw/typloc/torbernit.html|website=www.strahlen.org/tw}}<!-- auto-translated by Module:CS1 translator -->
</ref>
<ref name="Walenta">
K. Walenta: ''Beiträge zur Kenntnis seltener Arsenatmineralien unter besonderer Berücksichtigung von Vorkommen des Schwarzwaldes'' In: ''Tschermaks mineralogische und petrographische Mitteilungen (Mineralogy & Petrology)'' 1964, ''9'' (3), 252–282 ([https://link.springer.com/article/10.1007/BF01128088 online])
</ref>
<ref name="Webmineral">
{{cite web|author=David Barthelmy|date=2022-10-10|language=en|title=Torbernite Mineral Data|url=http://webmineral.com/data/Torbernite.shtml|website=webmineral.com}}<!-- auto-translated by Module:CS1 translator -->
</ref>
<ref name="Olds">
T. A. Olds, J. Plášil, A. R. Kampf, R. Škoda, P. C. Burns, J. Čejka, V. Bourgoin and J.-C. Boulliard: ''Gauthierite, KPb[(UO<sub>2</sub>)<sub>7</sub>O<sub>5</sub>(OH)<sub>7</sub>]·8H<sub>2</sub>O, a new uranyl-oxide hydroxy-hydrate mineral from Shinkolobwe with a novel uranyl-anion sheet-topology'' In: ''European Journal of Mineralogy'' 2017, ''20'', 129–141 ([https://www.schweizerbart.de/papers/ejm/detail/29/87388/Gauthierite_KPb%5BUO27_O5_OH7%5D_8H2_O_a_new_uranyl_oxide_hydroxy_hydrate_mineral_from_Shinkolobwe_with_a_novel_uranyl_anion_sheet_topology Weblink])
</ref>

</references>

== External links ==
{{Commons category|Torbernite}}
* {{cite web|access-date=2022-10-10|publisher=rruff.geo.arizona.edu|title=American-Mineralogist-Crystal-Structure-Database – Torbernite|url=http://rruff.geo.arizona.edu/AMS/result.php?mineral=Torbernite}}<!-- auto-translated by Module:CS1 translator -->
* {{cite web|access-date=2022-10-10|publisher=rruff.geo.arizona.edu|title=American-Mineralogist-Crystal-Structure-Database – Metatorbernite|url=http://rruff.geo.arizona.edu/AMS/result.php?mineral=Metatorbernite}}<!-- auto-translated by Module:CS1 translator -->
* {{cite web|access-date=2022-10-10|publisher=Database of Raman spectroscopy, X-ray diffraction and chemistry of minerals (rruff.info)|title=Metatorbernite search results|url=https://rruff.info/metatorbernite}}<!-- auto-translated by Module:CS1 translator -->

Category:Copper(II) minerals
Category:Uranium(VI) minerals
Category:Phosphate minerals
12
Category:Radioactive minerals
Category:Tetragonal minerals
Category:Minerals in space group 139

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Adapted from the Wikipedia article [Torbernite](https://en.wikipedia.org/wiki/Torbernite) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Torbernite?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.