is black, lustrous powder (MoS2) that serves as a dry-film lubricant in certain high-temperature and high-vacuum applications. It is also used in the form of pastes to prevent scoring when assembling press-fit parts, and as an additive to impart residual lubrication properties to oils and greases. Molybdenum disulfide is often called moly or molysulfide. It occurs as the mineral molybdenite. It is insoluble in water and unreactive toward dilute acids. Its melting point is 1185°C, but it starts oxidizing in air from 315°C, limiting the range of its use as a lubricant in the presence of air between the temperatures of -185°C and +350°C; in nonoxidizing environments it is stable up to 1100°C.

Also see fretting.