A hydration and metamorphic transformation of ultramafic rock from the Earth's mantle is called as serpentinization, a group of minerals is formed by serpentinization compose rock 'serpentinite'.
Troctolite is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with minor pyroxene. It is an olivine-rich anorthosite, or a pyroxene-depleted relative of gabbro