There were few mineral resources in Mauritius. Annual production in 2000 was estimated at 1 million tons of stone, 300,000 tons of sand, 7,000 tons of lime, and 6,000 tons of salt. Chemicals and metal products were leading industries in 2002. Historically, mineral output consisted of the local production and use of basalt construction stone, coral sand, lime for coral, and solar-evaporated sea salt. Concerns have been raised about the impact of coral sand mining on coastal lagoons. Polymetallic nodules occurred on the ocean floor, northeast of Tromelin Island, containing iron, manganese, and cobalt; however, these minerals were abundant on land. The near-term outlook for the exploitation of minerals other than construction materials was negligible.