VALLERIITE

    Class : Sulfides and sulfosalts
    Subclass : Sulfides
    Crystal system : Trigonal
    Chemistry : 4(Fe,Cu)S 3(Mg,Al)(OH)2
    Rarity : Rare

Valleriite is a rare mineral with a complex structure, in which layers of composition CuFeS2 (chalcopyrite) alternate with sheets of hydroxides of Mg, Al, Fe and sometimes Ni. Valleriite is formed by alteration of sulfides in ultrabasic rocks. It thus develops at the expense of chalcopyrite in chromitites of dunites (Cyprus deposit), or of copper-nickel sulfides in serpentinized peridotites and mafic stratified complexes. It commonly accompanies chromite, magnetite, pyrrhotite, pentlandite and millerite. It was named in honor of the Swedish mineralogist Goran Wallerius. Valleriite has a metallic luster and occurs in scaly masses with excellent cleavage, reminiscent of graphite, in thin incrustations and in small nodules. The dark bronze-yellow hue is reminiscent of pyrrhotite. Like graphite, valleriite stains paper because of its low hardness (1 to 1.5). It is an accessory ore of nickel.

Main photo : Valleriite from War Eagle Mine, Yukon, Canada © John Sobolewski

Valleriite in the World

Valleriite is known in exceptional masses of several kilos in the carbonatite of Palabora (South Africa) associated with magnetite, uraninite and apatite. The deposit of Eretria (Tessalie, Greece) has also provided very good specimens of valleriite.

Right photo : Valleriite from Traversella Mine, Piedmont, Italy © Tiziano Luzi


Valleriite in France

In France, valleriite is known in Argentine (Savoie) as well as in Corsican serpentinites around Corte.

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 1 to 1.5
Density : 3.14
Fracture : Undetermined
Streak : Black

TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : None