Djerfisherite

minerals

rasvumite

enstatite

tridymite

Images
Formula: K6(Fe,Cu,Ni)25S26Cl
Sulphide, djerfisherite group
Specific gravity:
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 duniteclinopyroxenite massif in the world. The exposed part is composed predominantly of serpentinised dunite. The sample with the most abundant djerfisherite is a phlogopitemagnetite-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:
pyrrhotiterasvumitedjerfisherite.
Sulfides of potassium in chloride-bearing clasts are considered to be primary phases crystallised from a kimberlitic melt (CM 46.1079-1095).

Back to Minerals