molybdenite

Molybdenite is a mineral and the principal ore of molybdenum. Its chemical formula is MoS2. It commonly forms as flat, plate-like crystals or foliated masses with a metallic luster and a lead-gray to bluish-black color. The mineral exhibits very perfect basal cleavage and has a Mohs hardness of about 1 to 1.5, making it very soft and easily exfoliated into thin sheets. It tends to occur in flexible, silvery sheets and has a specific gravity around 4.7.

The crystal structure consists of layers of molybdenum atoms sandwiched between sheets of sulfur. The layers are held together by weak van der Waals forces, which gives molybdenite its characteristic lubricity and easy cleavage. These layered sheets enable the material to disperse into fine flakes and contribute to its use as a dry lubricant. Molybdenite is stable at high temperatures and is relatively chemically resistant.

Occurrence and formation are linked to hydrothermal and high-temperature metamorphic environments. It is commonly found in hydrothermal ore veins and in association with quartz, pyrite, sphalerite, and galena, as well as in porphyry copper deposits. Worldwide occurrences are widespread, with notable production in several countries.

Uses and significance: molybdenite is the primary source of molybdenum, which is alloyed into steel and other metals to improve strength and resistance to corrosion. It also serves as a catalyst in hydrodesulfurization and other chemical processes, and its lubricating properties are exploited in lubricants and in research on two-dimensional materials.