As its name would imply, Molybdenite (molybdenum sulfide, or disulfide) is a molybdenum-bearing mineral; it is the most common source of the metal. “Moly Ore” as it is sometimes called, is a very soft metallic mineral (1 – 1.5 on the Mohs hardness scale, similar to Graphite/pencil lead), has a silver, lead-gray color, and a very high metallic luster. It has perfect cleavage in one direction, allowing thin crystals to be “peeled off” like a sheet of paper, much like the micas. Two distinct characteristics; it has a greasy feel due to its extreme softness, and the crystals can be easily bent. It is associated with numerous minerals, including Quartz, Fluorite, Pyrite, Calcite, Scheelite and Muscovite.
The crystal system for Molybdenite is hexagonal, forming hexagonal crystals, typically very thin and platy, occasionally irregular. Other forms include thick tabular, micaceous, foliated, scaly and massive.
Molybdenite is a relatively common mineral. Notable locations for quality specimens include Australia, Brazil, Canada, Japan, Norway and the USA (Utah, Washington).