Plancheite
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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.
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Plancheite | |
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General | |
Category | Inosilicate |
Formula (repeating unit) | Cu8Si8O22(OH)4•(H2O) |
IMA symbol | Pch[1] |
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[2][3][4] Nx = 1.697, Ny = 1.718, Nz = 1.741[5][6] |
Pleochroism | X colorless or pale blue, Y colorless or blue, Z blue or dark blue |
Other characteristics | Nonfluorescent, nonmagnetic, not radioactive |
References | [4][3][2][5] |
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