Molybdenite in quartz monzonite. Crystals of molybdenite, molybdenum disulphide, (silvery grey) in their monzonite host rock. Molybdenite is similar in appearance and feel to graphite. It has a lubricating effect due to its layered structure and is a common ore of molybdenum. Monzonite is an igneous intrusive rock composed of approximately equal quantities of plagioclase and orthoclase feldspars. Quartz monsonite is a form of monzonite that contains more than 10% quartz.