Molybdenite is a
mineral of
molybdenum disulfide,
MoS2. Similar in appearance and feel to
graphite, molybdenite 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. The Mo-S bonds are strong, but the interaction between the sulfur atoms at the top and bottom of separate sandwich-like tri-layers is weak, resulting in easy slippage as well as
cleavage planes. Molybdenite crystallizes in the
hexagonal crystal system as the common
polytype 2H and also in the
trigonal system as the 3R polytype.