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Rhode Island State Rock

Cumberlandite from Iron Mine Hill, east of Woonsocket, Rhode Island; photo by James St. John on Flickr (use permitted with attribution).

Official State Rock of Rhode Island

Rhode Island designated cumberlandite as the official state rock in 1966; a very rare variety of igneous rock. All State Rocks

Cumberlandite is magnetic and is estimated to be between 1 and 1.5 billion years old. A heavy black or dark brown rock with white markings, cumberlandite is found south of the town of Cumberland on both sides of Narragansett Bay in Rhode Island.