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Formula: 2[(Fe,Cu)S].1.53[(Mg,Al)(OH)2]
Sulphide, valleriite group
Crystal System: Trigonal
Specific gravity: 3.14 measured, 3.21 calculated
Hardness: 1 to 1½
Streak: Black
Colour: Dark grey-bronze-yellow
Common impurities: Ni,Ca,K,Na,Si
Environments
Carbonatites
Hydrothermal environments
Valleriite occurs as an alteration product of chalcopyrite in
chromatite and dunite
(Webmin),
associated with chalcopyrite,
cubanite,
pyrrhotite, troilite,
millerite, pentlandite,
pyrite, marcasite,
mackinawite, tochilinite and
magnetite
(HOM).
Localities
At the type locality, the Aurora mine, Kaveltorp Mines, Kopparberg, Ljusnarsberg, Örebro County, Sweden,
valleriite is found
in grains or as a felted fine grained aggregate in carbonate rock
(AM 18.224).
At Phalaborwa, Limpopo, South Africa, valleriite occurs in copper-bearing carbonatites, replacing
magnetite (HOM). In the carbonatite, valleriite is usually
associated with
magnetite or with ferroan spinel,
whereas in
the foskorite
(olivine/serpentine-
magnetite-apatite-
calcite rock) it generally occurs as coatings on other sulphides and is not
associated with magnetite. A specimen has been found where aggregates of
valleriite crystals are associated with calcite,
magnetite and iowaite, and in
another specimen
smears of valleriite are associated with
clinochlore, calcite, and
magnetite.
The formation temperature of valleriite is in excess of 225°C. At Palabora a late-stage alteration of the
orebody is believed
to have resulted in the deposition of valleriite along shear planes and other fractures, where it replaces all
other sulphides,
as well as magnetite, carbonate and silicate
gangue
(R&M 92-5.448-449).
In the basic rocks of the Bushveld complex valleriite has been found intimately intergrown with
chalcopyrite and pentlandite
(AM 18.224).
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