Oxidation states: Mo4+S2-2
Specific gravity: 4.7 to 4.8
Hardness: 1 - 1½
Streak: Dark grey
Solubility: Moderately soluble in sulphuric and nitric acid
Plutonic igneous 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.
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).
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