The process whereby high-temperature primary ferromagnesian minerals in an igneous rock undergo alteration to a member of the serpentine group of minerals. The process is initiated by the introduction of low-temperature water into the rock system, the water acting as a catalyst for the reaction in which the high-temperature primary ferromagnesian minerals are converted to low-temperature, secondary, serpentine-group minerals. Serpentinization is extremely common in ultrabasic rocks, especially those found in ophiolites where the entire rock may be converted to serpentine-group minerals, forming a serpentinite rock. Where the original mineral assemblage can be inferred from relict minerals or pseudomorph textures, the original mineral name can be added to the rock name. Thus a serpentinized dunite would be an olivine-serpentinite.