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Formula: MoS2
Sulphide
Oxidation states: Mo4+S2-2
Specific gravity: 4.7 to 4.8
Hardness: 1 - 1½
Streak: Dark grey
Colour: Lead-grey
Solubility: Moderately soluble in sulphuric and nitric acid
Environments:
Plutonic igneous environments
Pegmatites
Carbonatites
Metamorphic environments
Hydrothermal environments
Molybdenite forms as an accessory mineral in some igneous rocks and in pegmatites. It is found in
contact metamorphic deposits, and it is important in disseminated deposits of
the porphyry (with coarse crystals or mineral grains phenocrysts in a finer groundmass) type. It is common as a
primary mineral in
hypothermal (high temperature) hydrothermal veins.
Molybdenite may be found in some
granites, including
aplite
In contact metamorphic deposits it is associated with lime silicates,
scheelite and
chalcopyrite.
In hypothermal (high temperature) hydrothermal veins it is associated with
cassiterite,
scheelite,
hübnerite-ferberite
and
fluorite.
Localities
At Mount Moliagul, Moliagul, Central Goldfields Shire, Victoria, Australia, molybdenite occurs throughout the
aplite dykes and quartz veins in
the granodiorite, forming crystals up to 2 cm, sometimes associated
with muscovite
(AJM 21.1.43).
At the Faraday mine, Faraday Township, Hastings county, Ontario, Canada, molybdenite crystals to
8 cm across occur in small calcite veinlets
(R&M 94.5.414).
At the Sherlov mountain, Transbaikalia, Russia, molybdenite occurs with
ferrimolybdite
(FM 53392).
At Croft Quarry, Croft, Blaby, Leicestershire, England, UK, molybdenite occurs associated with
analcime, calcite,
laumontite and prehnite in a thin
granite pegmatite vein running through tonalite.
The molybdenite forms small foliated masses and nests of very thin plates, up to 3 mm in diameter. The plates are often strongly
malformed and curved round quartz and feldspar crystals
(JRS 20.21).
At the Main quarry, Mountsorrel, Leicestershire, England, UK, molybdenite occurs with
allanite and titanite on
granodiorite
(RES p192).
At the Childs-Adwinkle Mine, Copper Creek, Bunker Hill District, Pinal county, Arizona, USA, molybdenite occurs as crystals over 2 cm.
It typically occurs in quartz-rich veins with
chalcopyrite and pyrite
(R&M 96.2.155).
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