Plancheite

Plancheite
Plancheite
	Plancheite and Malachite, Milpillas mine, Sonora, Mexico
General
Category	Inosilicate
Formula; (repeating unit)	Cu8Si8O22(OH)4•(H2O)
IMA symbol	Pch
Strunz classification	9.DB.35 (10 ed) ; 8/F.05-10 (8 ed)
Dana classification	66.2.1.1
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) ; H-M symbol: (2/m 2/m 2/m)
Space group	Orthorhombic ; Space group: Pcnb
Identification
Formula mass	1,171 g/mol
Color	Pale blue, light blue, dark green
Crystal habit	Acicular, Fibrous, or Radial
Cleavage	None observed
Mohs scale hardness	5.5 to 6
Luster	Vitreous to silky
Streak	Light blue
Diaphaneity	Translucent to opaque
Specific gravity	3.6 to 3.8
Optical properties	Biaxial (+)
Refractive index	Nx = 1.645, Ny = 1.660 Nz = 1.715; Nx = 1.697, Ny = 1.718, Nz = 1.741
Pleochroism	X colorless or pale blue, Y colorless or blue, Z blue or dark blue
Other characteristics	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.

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ ^a ^b Mindat
^ ^a ^b Webmineral
^ ^a ^b Gaines et al (1997) Dana's New Mineralaogy, Wiley
^ ^a ^b Handbook of Mineralogy
^ Evans and Mrose (1977) American Mineralogist 62:491-502

[1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[mindat-2] Mindat

[webmin-3] Webmineral

[Dana-4] Gaines et al (1997) Dana's New Mineralaogy, Wiley

[HOM-5] Handbook of Mineralogy

[AM62-6] Evans and Mrose (1977) American Mineralogist 62:491-502

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