Mining and quarrying accounted for less than 1% of GDP, which grew by 7.9% in 2001, 5.4% in 2000, and 6.3% in 1999, and was expected to grow a further 5.8% and 6% in the following two fiscal years. Little of Ethiopia's expected mineral potential has been exploited, although foreign investment was increasing. Gold was the third-leading export commodity in 2002—5,200 kg mined in 2001, up from 2,500 in 1998 and 848 kg in 1990. Midroc Gold planned to start underground operations and to make upgrades to its processing plant at the Lega Dembi mine in 2001 that would increase gold production capacity from 2,800 kg per year to 4,700. Cement was the most important mineral industry in value and quantity. Also mined in limited quantities in 2001 were brick clay, kaolin, (China clay), common clays, columbium (niobium), diatomite, feldspar, semiprecious gemstones (fire opal, amethyst, peridot, rose quartz), gypsum and anhydrite, lignite, lime, pumice, rock salt, scoria, natural soda ash, stone, sand and gravel (crushed construction stone, dimension stone, granite, limestone, silica sand), talc, tantalum, and silver and platinum contained in gold ingots. Substantial iron ore deposits were discovered in the Welega region in 1985. Other undeveloped resources included copper, semiprecious gemstones (agate, aquamarine, chalcedony, chrysoprase, emerald, garnet, jasper, obsidian, ruby, sapphire, spinel), manganese, molybdenum, mercury, nickel, palladium, platinum, rhodium, tungsten, zinc, apatite, bentonite, dolomite, potash, and quartz sand. Expected improvements in the general economic situation and the need to rebuild infrastructure were likely to increase demand for building materials and the viability of Eritrea's metals and industrial minerals deposits.