The Manhattan schist is a formation of mica

Mica

The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...

 schist

Schist

The schists constitute a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a particular form called quartz schist is...

 rock that underlies much of the island of Manhattan

Manhattan

Manhattan is the oldest and the most densely populated of the five boroughs of New York City. Located primarily on the island of Manhattan at the mouth of the Hudson River, the boundaries of the borough are identical to those of New York County, an original county of the state of New York...

 in New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

. It is well suited for the foundations of tall buildings, and the two large concentrations of skyscrapers on the island occur in locations where the formation is close to the surface. At a third Manhattan location, in Central Park

Central Park

Central Park is a public park in the center of Manhattan in New York City, United States. The park initially opened in 1857, on of city-owned land. In 1858, Frederick Law Olmsted and Calvert Vaux won a design competition to improve and expand the park with a plan they entitled the Greensward Plan...

, protruded schist formations such as Rat Rock

Rat Rock

Rat Rock is a rock formation of a schist boulder protruding from the Central Park bedrock in Manhattan. It is named after the rats that used to swarm there at night but it is also known as Umpire Rock. It is near the southwest corner of the park, north of the Heckscher Ballfields on the lines of...

can be seen.

External links

• An Examination of Mica Schist by Andrea Samuels, Micscape magazine. Photographs of Manhattan schist.