In 2001, Luxembourg's mineral industry consisted primarily of raw materials processing, information systems, and mineral trading. The iron and steel industry was the most important mineral industry sector, ranking second among the nation's top industries in 2002; steel products ranked second among export commodities. Mining in Luxembourg was represented by small industrial mineral operations that produced material for domestic construction, including cement manufacture. These minerals included anhydrite, dimension stone, dolomite, gypsum, limestone, Thomas slag phosphates, sand and gravel, and slate. Chemicals ranked third among export commodities in 2002, and the manufacture of chemicals, metal products, glass, and aluminum were among the nation's leading industries. Luxembourg's traditional source of mineral wealth was iron ore, concentrated between Redange and Dudelange. Because of mine depletion, production declined from 2.08 million tons in 1976, to 429,000 in 1981, when the last iron mines were closed.