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Formula: K6(Fe,Cu,Ni)25S26Cl
Sulphide, djerfisherite group
Crystal System: Isometric
Hardness: 3½
Colour: Greenish yellow, khaki, to olive drab
Common impurities: Na,Mg
Environments:
Igneous envronments
Pegmatites
Metamorphic environments
Hydrothermal environments
Meteorites
Djerfisherite is present both in extraterrestrial enstatite chondrite or achondrite
meteorites, and in terrestrial alkaline intrusions,
kimberlites, hydrothermal
nickel-copper ore deposits,
skarns, pegmatites and a
mafic alkalic diatreme (a breccia-filled volcanic pipe that was formed by a gaseous
explosion)
(AM 99.1683–1693, HOM. Mindat, Webmin).
Localities
There are two co-type Localities:
the Kota-Kota meteorite, Nkhotakota, Central Region, Malawi
and
St. Mark's meteorite, Chris Hani District, Eastern Cape, South Africa
Djerfisherite occurs in these localities in enstatite
chondrites in grains O.02 to 0.4 mm in diameter. Associated
minerals include nickel-iron,
troilite, schreibersite,
clinoenstatite, tridymite,
cristobalite, daubréelite,
roedderite and alabandite
(AM 51.1815).
At the Elwin Bay kimberlite, Somerset Island, Nunavut, Canada, the Elwin Bay diatreme
(a breccia-filled volcanic pipe that was formed by a gaseous explosion) is an intrusion of
monticellite-calcite-serpentine
kimberlite. It contains abundant macrocrysts of
serpentinised olivine, rare macrocrysts of
phlogopite and titanian
pyrope, in a groundmass consisting of spinel,
perovskite and pyrite, set in
phlogopite-kinoshitalite,
calcite and primary
serpentine. The grains of djerfisherite occur as small crystals in the
kimberlite groundmass, suggesting that they are late
primary magmatic phases of this pipe. This contrasts with most described
examples of djerfisherite, which occur in mantle-derived xenoliths in
kimberlite, and in which they are normally
secondary after pyrrhotite and
pentlandite
(CM 32.815-823)
At the Gulinskii massif (Guli), Maimecha and Kotui Rivers Basin, Krasnoyarsk Krai, Russia, djerfisherite occurs in the
dunite portion of the complex, which is the largest
dunite–clinopyroxenite massif
in the world. The exposed part is composed predominantly of serpentinised
dunite. The sample with the most abundant djerfisherite is a
phlogopite–magnetite-rich
clinopyroxenite. Djerfisherite most commonly occurs in irregular patches
of sulphide composed mainly of pyrrhotite, accompanied by minor
chalcopyrite and rare galena, in a matrix of
titanium-bearing andradite,
clinopyroxene, phlogopite,
plagioclase, apatite and rare
zircon, titanite and
pyrophanite. The djerfisherite forms tiny crystals or grains, or it fills
fissures in the matrix and infiltrates phlogopite along its cleavage planes.
It is proposed that the djerfisherite crystallised as a primary mineral,
during the late-stage fractionation of a highly alkaline melt derived from an ascending mantle plume under metasomatic conditions
(CM 45.1201-1211).
At the Talnakh Cu-Ni Deposit, Noril'sk, Putoran Plateau, Taimyr Peninsula, Taymyrskiy Autonomous Okrug, Krasnoyarsk Krai, Russia,
djerfisherite occurs with talnakhite,
chalocopyrite, pentlandite,
magnetite, valleriite,
sphalerite and platinum minerals; it replaces
pentlandite
(AM 55.1071, HOM).
At the Udachnaya open-pit mine, Daldyn, Mirninsky District, Sakha Republic (Yakutia), Russia, chloride-bearing clasts from the
kimberlites contain rasvumite and
djerfisherite, which previously have been reported in the groundmass of the host
kimberlite. Djerfisherite is present in all types of chloride-containing
clasts, in which it rims pyrrhotite and forms grains and, more rarely,
octahedral crystals, at the contact with host kimberlite. The following sequence of
crystallisation was found:
pyrrhotite → rasvumite → djerfisherite.
Sulfides of potassium in chloride-bearing clasts are considered to be primary
phases crystallised from a kimberlitic melt
(CM 46.1079-1095).
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