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Formula: ReS2
Sulphide of rhenium, one of only two IMA-approved minerals that contain essential rhenium, the other one is tarkianite,
(Cu,Fe)(Re,Mo)4S8. Rhenium is a transition metal that was originally thought to occur in the
native state as tiny grains in wolframite from a Russian locality. It was later
discredited because of uncertain origin
(Mindat).
Crystal system: Triclinic
Specific gravity: 7.598 calculated
Streak: Grey-black
Colour: Silvery-white, black, red translucent
Environments
Fumeroles
Hydrothermal environments
Localities
At the Pagoni Rachi prospect, Alexandroupoli, Evros, Eastern Macedonia and Thrace, Greece, the Mo–Cu–Te–Ag–Au prospect
is a porphyry-epithermal system hosted by a
dacite porphyry and
quartz–feldspar
porphyry dikes. Rheniite and
molybdenite, with very high contents of
rhenium (up to 4.7 wt%), occur in quartz
veins along with Fe–Cu sulphides, Pb-, Sn-, and Cl-bearing oxides, hematite,
ilmenite and tellurides of
bismuth. Earlier-formed gold-bearing
quartz and magnetite veins with
sodic–potassic–calcic alteration and late precious-metal telluride-rich
carbonate–quartz veins with argillic alteration contain only minor amounts of
molybdenite. The composition of rheniite ranges from almost pure
rheniite with low Mo content to rheniite with up to 5.99 wt% Mo.
Rheniite and molybdenite likely precipitated as temperatures fell
below 400°C during phase separation under relatively oxidising conditions, at elevated chlorine activity, and from
relatively acid hydrothermal solutions. However, rheniite and Re-rich
molybdenite may have formed directly from the vapour as sublimates, in a
manner similar to the way they are deposited at the Kudriavy volcano, Kurile Islands
(CM 47.5.1013-1036).
At the type locality, the Kudriavy volcano, Iturup Island, Kurilsky District, Kuril Islands, Sakhalin Oblast, Russia,
rheniite occurs in the high temperature fumeraole as millimetric, wedge-shaped crystals that are dark red and
translucent. Associated minerals include andradite,
cadmoindite, corundum,
garnet group minerals,
greenockite, grossular,
halite, magnetite,
wollastonite and wurtzite
(Mindat).
Rheniite from the Kudriavy Volcano - Image
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