Molybdenite

Molybdenite is a mineral of molybdenum disulfide, MoS2. Similar in appearance and feel to graphite, it has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum atoms sandwiched between sheets of sulfur atoms.

Molybdenite is extremely soft with a metallic luster, and is superficially almost identical to graphite, to the point where it is not possible to positively distinguish between the two minerals without scientific equipment. It marks paper in much the same way as graphite. Its distinguishing feature from graphite is its higher specific gravity, as well as its tendency to occur in a matrix.

Molybdenite is an important ore of molybdenum, and is the most common source of the metal. While molybdenum is rare in the Earth’s crust, molybdenite is relatively common and easy to process, and accounts for much of the metal’s economic viability.