# Plancheite

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{{Short description|Hydrated copper silicate mineral}}
{{Infobox mineral
| name        = Plancheite
| category    = [Inosilicate](/source/Inosilicate)
| image       = Plancheite and Malachite.jpg
| caption     = Plancheite and Malachite, Milpillas mine, [Sonora](/source/Sonora), Mexico
| imagesize   = 300px
| formula     = Cu<sub>8</sub>Si<sub>8</sub>O<sub>22</sub>(OH)<sub>4</sub>•(H<sub>2</sub>O)
| IMAsymbol   = Pch<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   = 1,171 g/mol
| strunz      = 9.DB.35 (10 ed) <br /><small>8/F.05-10 (8 ed)</small>
| dana        = 66.2.1.1
| system      = [Orthorhombic](/source/Orthorhombic) 
| class       = Dipyramidal (mmm) <br/>[H-M symbol](/source/H-M_symbol): (2/m 2/m 2/m)
| symmetry    = Orthorhombic <br/>[Space group](/source/Space_group): ''Pcnb''
| color       = Pale blue, light blue, dark green
| habit       = Acicular, Fibrous, or Radial
| twinning    =
| cleavage    = None observed
| fracture    =
| mohs        = 5.5 to 6
| luster      = Vitreous to silky
| refractive  =  Nx = 1.645, Ny = 1.660 Nz = 1.715<ref name=mindat/><ref name=webmin/><ref name=Dana/><br/>
                Nx = 1.697, Ny = 1.718, Nz = 1.741<ref name=HOM/><ref name=AM62>Evans and Mrose (1977) American Mineralogist
                62:491-502</ref>
| birefringence =
| pleochroism = X colorless or pale blue, Y colorless or blue, Z blue or dark blue
| streak      = Light blue
| gravity     = 3.6 to 3.8
| melt        =
| fusibility  =
| diagnostic  =
| opticalprop = Biaxial (+)
| solubility  =
| diaphaneity = Translucent to opaque
| other       = Nonfluorescent, nonmagnetic, not radioactive
| references  =<ref name=Dana>Gaines et al (1997) Dana's New Mineralaogy, Wiley</ref><ref name=webmin>[http://www.webmineral.com/data/Plancheite.shtml Webmineral]</ref><ref name=mindat>[http://www.mindat.org/min-3233.html Mindat]</ref><ref name=HOM>[http://www.handbookofmineralogy.org/pdfs/plancheite.pdf Handbook of Mineralogy]</ref>}}

'''Plancheite''' is a hydrated [copper](/source/copper) [silicate](/source/silicate) [mineral](/source/mineral) with the formula [Cu](/source/Copper)<sub>8</sub>[Si](/source/Silicon)<sub>8</sub>[O](/source/Oxygen)<sub>22</sub>([OH](/source/Hydroxide))<sub>4</sub>•([H<sub>2</sub>O](/source/Properties_of_water)). It is closely related to [shattuckite](/source/shattuckite) in structure and appearance, and the two minerals are often confused.

==Structure==
Plancheite is a [chain silicate](/source/silicate_minerals) ([inosilicate](/source/inosilicate)), with double chains of silica [tetrahedra](/source/tetrahedra) parallel to the c crystal axis.<ref name=AM62/>   It occurs as sprays of acicular or fibrous radial clusters, with fibers extended parallel to the chains, i.e. along the c crystal axis;<ref name=HOM/> it can also form tiny tabular or platy crystals.  It is a member of the [orthorhombic crystal class](/source/orthorhombic_crystal_system) m m m (2/m 2/m 2/m), which is the most symmetrical class in the orthorhombic system.

==Properties==
Usually a pale turquoise-blue, with a pale blue streak and an adamantine to silky [luster](/source/Lustre_(mineralogy)). It is quite hard, with hardness 5.5 to 6, close to that of feldspar, and specific gravity 3.6 to 3.8.  Optically it is [biaxial (+)](/source/birefringence), with [refractive indices](/source/refractive_indices) between 1.64 and 1.74, and [pleochroic](/source/pleochroic).<ref name="mindat"/><ref name="webmin"/><ref name="Dana"/><ref name="HOM"/>

==Environment==
Plancheite is a secondary mineral formed in the [oxidized zone](/source/oxidized_zone) of copper deposits, associated with other copper minerals [chrysocolla](/source/chrysocolla), [dioptase](/source/dioptase), [malachite](/source/malachite), [conichalcite](/source/conichalcite) and [tenorite](/source/tenorite).<ref name=HOM/>  It occurs with primary malachite at the Milpillas Mine in Mexico.<ref name=MinRec39>Moore and Origlieri (2008) Mineralogical Record 39-6:25-34</ref>  The type locality is the Sanda Mine, Mindouli, Pool Region, Republic of Congo.<ref name=mindat/>
[[File:Plancheite-35235.jpg|thumb|left|Plancheite, [Kolwezi](/source/Kolwezi), [Katanga](/source/Katanga_Province) (Shaba), Democratic Republic of Congo. 5.9 x 3.2 x 2.6 cm.]]

{{clear}}
==References==
{{Reflist}}

==External links==
JMol: http://rruff.geo.arizona.edu/AMS/viewJmol.php?id=00578

{{Commons category}}

Category:Copper(II) minerals
Category:Inosilicates

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