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Formula: PdCu
Alloy of palladium and copper
Crystal system: Isometric
Specific gravity: 10.64 calculated for the empirical formula
Hardness: 4 to 5
Streak: Black
Colour: Steel-grey
Environments
Skaergaardite occurs in mafic-ultramafic layered intrusions associated with
sulphide minerals possibly formed from immiscible melts
(HOM).
Localities
At the type locality, the Skaergaard intrusion, Kangerlussuaq Fjord, Sermersooq, Greenland, skaergaardite occurs in a
well-preserved, oxide-rich, tholeitic
gabbro. The associated
platinum group element and gold
mineralisation is stratiform in nature. The gabbro hosting the
skaergaardite is composed of plagioclase,
clinopyroxene, orthopyroxene,
ilmenite, titanium-bearing
magnetite and fayalite, as the
rock-forming minerals, and small amounts of accessory chlorite group minerals,
ferrosaponite, a member of the
annite–phlogopite series,
hornblende, actinolite,
epidote group minerals, calcite,
ankerite, apatite and
baddeleyite.
The skaergaardite is found in composite microglobules composed of bornite,
chalcocite, digenite and
chalcopyrite, with rare
cobaltpentlandite, sphalerite,
keithconnite, vasilite,
zvyagintsevite, (Cu,Pd,Au) and (Pt-Fe-Cu-Pd) alloys, and unnamed
PdCu3, (Pd,Cu,Sn), Au3Cu and PdAuCu. Skaergaardite may be found as inclusions in
titanium-bearing magnetite,
ilmenite, pyroxenes and
plagioclase.
While skaergaardite is the dominant platinum group mineral in the
environment, representing more than 90% of the total platinum group minerals
observed, other platinum group and precious-metal bearing minerals are present
(both as inclusions in skaergaardite and as discrete grains) including
keithconnite, vasilite and
zvyagintsevite
(MM 68.4.615-632).
Skaergaardite from the Kangerlussuaq Fjord -
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