Molybdenite

sulphide

primary mineral

Formula: MoS2 Sulphide
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.

At the Main quarry, Mountsorrel, Leicestershire, England, UK, molybdenite occurs with allanite and titanite on granodiorite (RES p192).

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