Molybdenite - Encyclopedia

Class : Sulfide and sulfosalt
Subclass : Sulfide
Crystal System : Hexagonal
Chemistry : Mo₂S₂
Rarity : Quite common

Molybdenite is a common primary sulphide in high temperature hydrothermal deposits (copper porphyries, skarns, pneumatolytic veins) and granitic pegmatites. It owes its name to the Greek molubdos (lead) as a result of a confusion of ancient authors between galena, graphite and this mineral. It has a metallic luster, a gray color and a perfect lamellar cleavage. Molybdenite occurs as hexagonal, often deformed and frequently included, tabular crystals, as well as thin, flexible lamellae. Of low hardness (1 to 1.5), molybdenite has a creamy touch and written on paper or porcelain. This mineral is one of the only molybdenum ore but also rhenium ore, present in small amounts in the crystal lattice of this mineral.

Molybdenite in quartz from Moly Hill mine, Quebec, Canada

Molybdenite from Striegau, Poland

Molybdenite in the World

Although this mineral is relatively common the good samples are rare. The most beautiful known single crystals (lamellar groups up to 12 cm in diameter on quartz) come from Sach's and Giant Blast (Australia) and to a lesser extent from Taewha (South Korea) with crystals in rosettes of 5 cm. In all other localities, it is most often crystals included in quartz : 8 cm diameter lamellae in Ross, Ontario and Aldfield (Canada). They are found in quartz also in Norway, in Bandaksli and Raade (where the crystals reach 15 cm) or in the USA, Lake Chelan (Washington) with 5 cm crystals.

Molybdenite in France

In France, it is known in centimetric crystals in several tin-tungsten deposits such as Montbelleux (Ille-et-Vilaine) and Château-Lambert (Vosges), as well as in the pegmatites of Ploumanac'h granites (Côtes d'Armor) .

Twinning

No known twinning for this species.

Fakes and scams

No fake inventories for this species.

Hardness : 1 to 1.5
Density : 4.62 to 4.73
Fracture : Flexible

Trace : Bluish-gray

TP : Opaque
IR : -
Biréfringence : -
Caractère optique : -
Pléochroïsme : -
Fluorescence : None

Solubilité : Nitric acid

Magnétisme : None
Radioactivité : None