Spertiniite

Spertiniite is a rare copper hydroxide mineral. Chemically, it is copper(II) hydroxide with the formula Cu(OH)2. It occurs as blue to blue-green tabular orthorhombic crystal aggregates in a secondary alkaline environment altering chalcocite. Associated minerals include chalcocite, atacamite, native copper, diopside, grossular, and vesuvianite.

Spertiniite
Spertiniite from Dzhezkazgan, Kazakhstan (size: 5 mm)
General
CategoryOxide mineral
Formula
(repeating unit)
Cu(OH)2
IMA symbolSni
Strunz classification4.FD.05
Dana classification6.2.4.1
Crystal systemOrthorhombic
Crystal classPyramidal (mm2)
H-M symbol: (mm2)
Space groupCmc21
Unit cella = 2.95 Å, b = 10.59 Å
c = 5.27 Å; Z = 4
Identification
Formula mass97.56 g/mol
ColorBlue, blue-green
Crystal habitFlat tabular crystals occurring in radial to botryoidal aggregates
CleavageNone
TenacityBrittle
Mohs scale hardnessSoft
LusterVitreous
DiaphaneityTransparent
Specific gravity3.93
Optical propertiesBiaxial
Refractive indexnα = 1.720, nβ= n.d., nγ = > 1.800
PleochroismStrong; X = colorless; Z = dark blue
Other characteristicsDecomposes in hot water (synthetic)
References
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