Essexite

Essexite (/ˈɛsəkˌsaɪt/), also called nepheline monzogabbro (/ˈnɛfəˌlɪn ˌmɒnzoʊˈɡæbroʊ, -ˌliːn-/), is a dark gray or black holocrystalline plutonic igneous rock. Its name is derived from the type locality in Essex County, Massachusetts, in the United States.