The serpentinite has a bluish to greenish gray color, and consists of serpentine (mostly the variety antigorite), with accessory minerals of chrysotile (a form of asbestos), magnetite, and talc. Serpentinite is derived by the metamorphism of ultramafic rocks (rocks rich in the minerals olivine and pyroxene) in a water-rich environment. The probable original setting for these rocks was within the igneous crust beneath the Iapetus Ocean. The occurrence of serpentinite in the core of Staten Island is an indication that the allochthonous basement rocks consisting of oceanic crustal material were thrust landward onto the eastern margin of the continent during the Taconic orogeny. The occurrence of serpentinite is consistent with the interpretation that Staten Island is east of Cameron's Line.
