Valleriite

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Valleriite
Cubanite-Maucherite-Valleriite-199922.jpg
Cubanite (brass yellow), maucherite (dark gray) and valleriite (dark bronze), mainly.
General
CategorySulfide mineral
Formula
(repeating unit)
(Fe2+,Cu)4(Mg,Al)3S4(OH,O)6
Strunz classification2.FD.30
Dana classification2.14.1.1
Crystal systemTrigonal[1]
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupR3m
Unit cella = 3.79, c = 34.1 [Å]; Z = 2
Identification
ColorBronze-yellow, gray
Crystal habitMassive, nodular, encrustations, thin splintery
CleavageExcellent on {0001}
Mohs scale hardness1 - 1.5
LusterMetallic
StreakBlack
DiaphaneityOpaque
Specific gravity3.14 (measured)
PleochroismStrong; pale yellow to deep brown
References[2][3][1]

Valleriite is an uncommon sulfide mineral (hydroxysulfide) of iron and copper with formula: 4(Fe,Cu)S·3(Mg,Al)(OH)2[3] or (Fe2+,Cu)4(Mg,Al)3S4(OH,O)6.[2] It is an opaque, soft, bronze-yellow to brown mineral which occurs as nodules or encrustations.

Discovery and occurrence[edit]

Valleriite was first described in 1870 from an occurrence in Västmanland, Sweden. It was named for Swedish chemist Johan Gottschalk Wallerius (Vallerius) (1709–1785).

Valleriite occurs in dunites and chromitites replacing chalcopyrite in Cyprus. In Phalaborwa, South Africa it occurs as replacement of magnetite in a carbonatite. It occurs as replacements of copper and nickel phases in serpentinites and other altered ultramafic rocks.[3]

References[edit]