Mossoró is the second most populous city in the state of Rio Grande do Norte, Brazil, and also the largest municipality of that state. It is equid…Mossoró is the second most populous city in the state of Rio Grande do Norte, Brazil, and also the largest municipality of that state. It is equidistant from Natal, the state capital of Rio Grande do Norte, and from Fortaleza, the capital of the state of Ceará. It is also in the heart of Brazil's salt production area. Situated in the Oeste Potiguar mesoregion, Mossoró is the country's largest land-based petroleum producer.