thumb|right|Specimen of cumberlandite on display at the Roger Williams Park Museum of Natural History and Planetarium. Specimen is approximately 1 foot (30 cm) wide. Cumberlandite is a specific type of plutonic rock called a melanocratic troctolite, or melatroctolite. It is the state rock of Rhode Island and can be found in a lot in Cumberland, Rhode Island at Iron Mine Hill. Further traces can be found scattered throughout the Narragansett Bay watershed as far as Martha's Vineyard and Block Island. Cumberlandite is not exclusive to Rhode Island; it is also found in Taberg, Sweden. It is sligh
thumb|right|Specimen of cumberlandite on display at the Roger Williams Park Museum of Natural History and Planetarium. Specimen is approximately 1 foot (30 cm) wide. Cumberlandite is a specific type of plutonic rock called a melanocratic troctolite, or melatroctolite. It is the state rock of Rhode Island and can be found in a lot in Cumberland, Rhode Island at Iron Mine Hill. Further traces can be found scattered throughout the Narragansett Bay watershed as far as Martha's Vineyard and Block Island. Cumberlandite is not exclusive to Rhode Island; it is also found in Taberg, Sweden. It is slightly ferrimagnetic due to its high concentration of iron.
==Background== Colonial settlers recognized its value as ore during the 18th and 19th centuries. Historical records reveal that it was smelted as early as 1703, and it was used in forging cannons during significant events such as the Siege of Louisbourg in 1745 and possibly the American Revolutionary War.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).