Schmiederite

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Schmiederite
Schmiederite-107145.jpg
General
CategorySelenate minerals
Formula
(repeating unit)
Pb2Cu2(Se4+
O
3
)(Se6+
O
4
)(OH)4
Strunz classification7.BC.65
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/m
Unit cella = 9.92 Å, b = 5.71 Å
c = 9.36 Å; β = 101.86°; Z = 2
Identification
ColorPale to deep Prussian blue
Crystal habitFibrous in radial clusters; may be in crusts; powdery
LusterSubadamantine to satiny
StreakLight blue
DiaphaneityTransparent
Specific gravity5.62
Optical propertiesBiaxial (+)
Refractive indexnα = 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.[2][3]

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]