almandine

apophyllite

Minerals of New York City

Over millions of years, sediments were deposited together with volcanic rocks into a shallow sea that covered the eastern part of proto-North America. During the Taconic Orogeny (~450 million years ago) an island arc similar to the present day Japanese archipelago, moved toward and collided with the American continent. The collision subjected the rocks to high pressures and to temperatures of around 700 degrees C and transformed them, through metamorphism, into the crystalline schists that built Manhattan Island. Also, during that collision, fragments of the oceanic crust were pushed onto the continent and now constitute parts of Staten Island.

Temperature, pressure, and fluids reorganized the composition of the rocks and generated many different mineral species, such as garnet, feldspar, chrysoberyl, and tourmaline. When the bedrock relaxed after the peak of the Taconic Orogeny, some of the earlier formed minerals became unstable and were replaced by minerals stable at surface conditions such as calcite, stilbite, apophyllite and artinite.

This display case highlights some of the over 129 different mineral species that have been recognized as occurring in New York City.

NY City minerals case

artinite stilbite stilbite

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