Schist (Manhattan Schist or Hartland Formation, late Neoproterozoic or Cambrian-Ordovician; Manhattan Island, New York City, New York State, USA)
Schist from New York State, USA. (4.6 centimeters across at its widest)
Manhattan Island, in the heart of New York City, seems prima facie an unlikely place for seeing geology. However, nice rock outcrops occur in several city parks, including the largest, Central Park. The bedrock in Manhattan is principally high-grade metamorphic rocks, such as gneisses, schists, and marbles. The rock seen here is a mica-rich schist that comes from either the late Neoproterozoic Manhattan Schist or the Cambrian-Ordovician Hartland Formation.
Locality: unrecorded site on Manhattan Island, New York City, southeastern New York State, USA