Collection: Molybdenite

Molybdenite, also known as “Moly Ore,” is the natural form of molybdenum disulfide (MoS₂). This soft, metallic mineral is easily mistaken for graphite due to its appearance and greasy feel, but it can be distinguished by its bluish-silver color and streak, compared to the darker black-silver tones and gray streak of graphite.

Before molybdenum was recognized as a distinct element in 1778 by Karl Wilhelm Scheele, molybdenite was often misidentified as graphite or a lead ore. The mineral’s name comes from the Greek word “molybdos,” meaning “lead,” in reference to its metallic sheen.

Structurally, molybdenite is composed of alternating layers of molybdenum and sulfur. The sulfur atoms bond strongly to molybdenum but weakly to other sulfur layers, creating its characteristic softness and perfect cleavage. It can easily leave a mark on paper and has a smooth, greasy texture. Despite its softness, it displays a brilliant metallic luster, making it a striking and educational addition to any mineral collection.

Molybdenite is the primary ore of molybdenum and occurs in a wide range of geological settings, including contact metamorphosed limestones, granites, pegmatites, fine-grained igneous rocks, and high-temperature hydrothermal veins. It is also found in disseminated porphyry deposits, which are important commercial sources of molybdenum.

Notably, molybdenite has even been discovered in meteorites, underscoring its geologic significance. Fine specimens have been found in the United States, Canada, Norway, Russia, Germany, Morocco, Australia, and Japan.