Plancheite

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title: "Plancheite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["copper(ii)-minerals", "inosilicates"] description: "Hydrated copper silicate mineral" topic_path: "general/copper-ii-minerals" source: "https://en.wikipedia.org/wiki/Plancheite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Hydrated copper silicate mineral ::

::data[format=table title="Infobox mineral"]

Field	Value
name	Plancheite
category	Inosilicate
image	Plancheite and Malachite.jpg
caption	Plancheite and Malachite, Milpillas mine, Sonora, Mexico
imagesize	300px
formula	Cu8Si8O22(OH)4•(H2O)
IMAsymbol	Pch
molweight	1,171 g/mol
strunz	9.DB.35 (10 ed)
8/F.05-10 (8 ed)
dana	66.2.1.1
system	Orthorhombic
class	Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
symmetry	Orthorhombic
Space group: Pcnb
color	Pale blue, light blue, dark green
habit	Acicular, Fibrous, or Radial
cleavage	None observed
mohs	5.5 to 6
luster	Vitreous to silky
refractive	Nx = 1.645, Ny = 1.660 Nz = 1.715

| | Nx | 1.697, Ny = 1.718, Nz = 1.741Evans and Mrose (1977) American Mineralogist | | pleochroism | X colorless or pale blue, Y colorless or blue, Z blue or dark blue | | streak | Light blue | | gravity | 3.6 to 3.8 | | opticalprop | Biaxial (+) | | diaphaneity | Translucent to opaque | | other | Nonfluorescent, nonmagnetic, not radioactive | | references | | ::

| name = Plancheite | category = Inosilicate | image = Plancheite and Malachite.jpg | caption = Plancheite and Malachite, Milpillas mine, Sonora, Mexico | imagesize = 300px | formula = Cu8Si8O22(OH)4•(H2O) | IMAsymbol = Pch | molweight = 1,171 g/mol | strunz = 9.DB.35 (10 ed) 8/F.05-10 (8 ed) | dana = 66.2.1.1 | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Orthorhombic 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

Nx = 1.697, Ny = 1.718, Nz = 1.741Evans and Mrose (1977) American Mineralogist 62:491-502 | 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 =}}

Plancheite is a hydrated copper silicate mineral with the formula Cu8Si8O22(OH)4•(H2O). It is closely related to shattuckite in structure and appearance, and the two minerals are often confused.

Structure

Plancheite is a chain silicate (inosilicate), with double chains of silica tetrahedra parallel to the c crystal axis. It occurs as sprays of acicular or fibrous radial clusters, with fibers extended parallel to the chains, i.e. along the c crystal axis; it can also form tiny tabular or platy crystals. It is a member of the orthorhombic crystal class 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. 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 (+), with refractive indices between 1.64 and 1.74, and pleochroic.

Environment

Plancheite is a secondary mineral formed in the oxidized zone of copper deposits, associated with other copper minerals chrysocolla, dioptase, malachite, conichalcite and tenorite. The type locality is the Sanda Mine, Mindouli, Pool Region, Republic of Congo. ::figure[src="https://upload.wikimedia.org/wikipedia/commons/9/98/Plancheite-35235.jpg" caption="Katanga]] (Shaba), Democratic Republic of Congo. 5.9 x 3.2 x 2.6 cm."] ::

References

References

1. Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
2. Gaines et al (1997) Dana's New Mineralaogy, Wiley
3. [http://www.webmineral.com/data/Plancheite.shtml Webmineral]
4. [http://www.mindat.org/min-3233.html Mindat]
5. [http://www.handbookofmineralogy.org/pdfs/plancheite.pdf Handbook of Mineralogy]
6. It occurs with primary malachite at the Milpillas Mine in Mexico.Moore and Origlieri (2008) Mineralogical Record 39-6:25-34

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