In 2001, mineral production in Liberia consisted mainly of artisanal recovery of diamond and gold. Since December 1989, when mining revenues accounted for 22% of GDP, the mining sector has been severely damaged by civil war. By 1991, a single iron ore mine, operated by the Iron Mining Company of Liberia (LIMCO), was one of only a few industrial operations functioning in the entire country. Liberia had significant reserves of moderate-grade iron ore, the country's third-leading export commodity, which could be exploited after the limited reserves near Yekepa and Bong become exhausted. Diamonds comprised the fourth-leading industy and export commodity in 2002. Estimated production of gold in 2001 was 1,000 kg, up from 500 in 1997, during the civil war; and of diamonds, 170,000 carats, down from 300,000 in 1998. In 2001, the country also produced hydraulic cement, clays, gypsum, sand and gravel, and stone. Liberia's undeveloped resources included barite, chromium, kyanite, manganese, nickel, palladium, plantinum, titaniferous sands, and uranium. In 2001, Mano River Resources announced the discovery of its sixth kimberlite pipe in western Liberia since beginning exploration in 2000. The company believed that the artisanal diamond workings in the area, which have yielded a number of high-quality diamonds, were located on top of their newly discovered kimberlite. Manos River continued exploration at its Gondoja, King George-Larjor, and Weaju properties after having made several gold discoveries in 2000; resources at King George-Larjor were estimated to be 4.1 million tons at a grade of 4.6 grams per ton of gold, and those at Weaju, 660,000 tons at a grade of 10.9 grams per ton. In 2000 the UN caledl for an embargo on all diamond exports from Liberia, owing to its potential involvement in civil unrest in Sierra Leone. In 2001, Liberia's president pressed the National Legislature to grant him control over mineral resources via the Strategic Commodities Act. Prior to that, the Ministry of Lands, Mines, and Energy was responsible for the administration of the mining sector. A new Mineral Development Policy and Mining Code outlined five types of mining license—reconnaissance, exploration, Class A (for small-scale alluvial operations, available for Liberians only), Class B (for 5 years), and Class C (for 25 years, requiring a feasibility report). Eastern Liberia was made up of rocks of Birimian age with significant potential for gold. Western Liberia was made up of rocks of Archean age that contained diamond, gold, iron ore, nickel, manganese, palladium, plantinum, and uranium.