Schmiederite

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Schmiederite
Schmiederite-107145.jpg
Schmiederite
General
Category Selenate minerals
Formula
(repeating unit)
Pb2Cu2(Se4+
O
3
)(Se6+
O
4
)(OH)4
Strunz classification 07.BC.65
Crystal symmetry Monoclinic prismatic
H-M symbol: (2/m)
Space group: P 21/m
Unit cell a = 9.92 Å, b = 5.71 Å, c = 9.36 Å; β = 101.86°; Z = 2
Identification
Color Pale to deep Prussian blue
Crystal habit Fibrous in radial clusters; may be in crusts; powdery
Crystal system Monoclinic
Luster Subadamantine to satiny
Streak Light blue
Diaphaneity Transparent
Specific gravity 5.62
Optical properties Biaxial (+)
Refractive index nα = 1.85–1.9 nβ = 1.9–1.95 nγ = 1.95–2.1
References [1][2][3]

Schmiederite is a secondary mineral in the oxidized zone of selenium-bearing hydrothermal base metal deposits. Its chemical formula is Pb2Cu2(Se4+O3)(Se6+O4)(OH)4.[3][2]

It was first described in 1962 for an occurrence in the Cóndor mine, Los Llantenes district, Sierra de Cacheuta, La Rioja Province, Argentina (type locality). It was named for Oscar Schmieder (1891–1980), German geographer.[2]

References[edit]